Concentration Of Methacholine Research Articles

Effect and mechanism of acupuncture on airway smooth muscle relaxation during acute asthma attack in rats.

To explore the effect and mechanism of acupuncture at "Feishu" (BL 13) and "Dingchuan" (EX-B 1), and "Kongzui" (LU 6) and "Yuji" (LU 10) for relaxing the airway smooth muscle in the rats during acute asthma attack and compare the effect among the two pairs of acupoints and the acupoints combination. Forty SD male rats with SPF grade were randomly divided into a blank group, a model group, a pair-point A group (acupuncture at "Feishu" [BL 13] and "Dingchuan" [EX-B 1]), a pair-point B group (acupuncture at "Kongzui" [LU 6] and "Yuji" [LU 10]) and a point combination group (acupuncture at "Feishu" [BL 13] , "Dingchuan" [EX-B 1], "Kongzui" [LU 6] and "Yuji" [LU 10]), with 8 rats in each group. Except the rats in the blank group, the model of acute asthma attack was induced by ovalbumin (OVA) combined with aluminum hydroxide gel in the rest groups. Started on the 15th day of modeling, except in the blank group and the model group, acupuncture was delivered in the other groups, 30 min in each intervention, once daily, for 14 days. In each group, the latent period of asthma inducing was measured; the lung resistance (LR) and dynamic lung compliance (Cdyn) were determined using lung function detector; the levels of endothelin-1 (ET-1), tumor necrosis factor-α (TNF-α), cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) in serum and bronchoalveolar lavage fluid (BALF) were measured by ELISA; with Masson staining and electron microscopy adopted, the morphology and ultrastructure of airway smooth muscle of the rats were observed; the mRNA and protein expressions of ET-1 and beta-2 adrenergic receptor (β2-AR) were detected by quantitative real-time fluorescence and Western blot, respectively. Compared with the blank group, the latent period of asthma inducing was shortened (P<0.05), RL increased and Cdyn decreased (P<0.05) with the different concentrations of methacholine (0.025 mg/kg, 0.05 mg/kg, 0.1 mg/kg, 0.2 mg/kg) in the model group. In the pair-point A group, the pair-point B group and the point combination group, the latent period of asthma inducing was prolonged (P<0.05), RL decreased and Cdyn increased (P<0.05) with different concentrations of methacholine when compared with those in the model group; and the latent period of asthma inducing in the point combination group was longer than that in the pair-point A group (P<0.05). Compared with the blank group, the levels of ET-1, TNF-α and cGMP in the serum and BALF were elevated (P<0.05), and those of cAMP reduced (P<0.05) in the model group. The levels of ET-1, TNF-α and cGMP in the serum and BALF were reduced (P<0.05), and those of cAMP elevated (P<0.05) in the pair-point A group, the pair-point B group and the point combination group when compared with those in the model group. In the blank group, the lung tissue was normal structurally. In the model group, the collagen fibers were proliferated increasingly, the smooth muscle was thickened, the mitochondria were swollen, and their cristae disrupted and reduced massively. In the pair-point B group, the collagen fibers were proliferated, the smooth muscle was thicker compared with that in the blank group, the mitochondria were mildly swollen and their cristae disrupted partially. In the pair-point A group and the point combination group, the lung tissue changes were obviously alleviated in comparison with the model group, the mitochondria were slightly swollen and their cristae disrupted occasionally. Compared with the blank group, the mRNA and protein expression of ET-1 increased and that of β2-AR decreased in the lung tissue of the model group (P<0.05). In the pair-point A group, the pair-point B group and the point combination group, the mRNA and protein expression of ET-1 was reduced and that of β2-AR elevated in the lung tissue when compared with those in the model group (P<0.05). In comparison with the pair-point A group, the mRNA expression of β2-AR was elevated in the point combination group (P<0.05). When compared with the pair-point B group, the mRNA expression of β2-AR increased, the protein expression of ET-1 decreased (P<0.05) in the point combination group. Acupuncture at "Feishu" (BL 13) and "Dingchuan" (EX-B 1), "Kongzui" (LU 6) and "Yuji" (LU 10), two pairs of acupoints relieves the airway smooth muscle spasm in the rats during acute asthma attack, which may be related to inhibiting the mRNA and protein expression of ET-1 to reduce the excretion of ET-1 and TNF-α; while enhancing the mRNA and protein expression of β2-AR to balance the levels of cAMP and cGMP. The effect is optimal when acupuncture is delivered at two pairs of acupoints simultaneously.

Standard technical specifications for methacholine chloride (Methacholine) bronchial challenge test (2023)

Standard technical specifications for methacholine chloride (Methacholine) bronchial challenge test (2023)

Presence of variable extrathoracic airflow limitation in patients with a negative methacholine challenge test

PurposeDetermine whether variable extrathoracic airflow limitation (VEAL) is observed in patients with negative methacholine challenge tests (MCT).MethodsElectronic medical records of patients undergoing MCT at Jesse Brown VA Medical Center between January 2017 and December 2019 were reviewed. Only patients with negative MCT were selected. Pertinent demographic, clinical, and pulmonary function tests (PFT) and MCT data were abstracted from each record. Spirometric flow-volume loops recorded during each test were inspected by one co-author to determine the first inhaled methacholine concentration at which FEF50/FIF50 was either > 1 or further increased if baseline FEF50/FIF50 after nebulized saline (vehicle) already exceeded 1. Student’s t-test was used for statistical analysis. P < 0.05 was considered statistically significant.ResultsOne hundred and twenty-seven consecutive patients with normal baseline PFT and negative MCT were identified. Thirteen patients (10.2%) had negative MCT and FEF50/FIF50 > 1 after testing. They were predominately obese (BMI, 31.3 ± 6.6), non-smoking (10), White (8) males (9) aged 51.3 ± 14.1 years (mean ± SD) referred for symptoms suggestive of asthma (n = 7) or for chronic cough (n = 6). Five had obstructive sleep apnea, three gastroesophageal reflux disease, and two chronic rhinosinusitis. FEF50/FIF50 increased significantly from 0.72 ± 0.21 after nebulized saline (vehicle) to 1.21 ± 0.13 after inhaled methacholine (p < 0.001). Median inhaled methacholine concentration eliciting these responses was 1.0 mg/mL (range, 0.25–16 mg/mL).ConclusionsVEAL is observed in a subset of patients with a negative MCT. This phenomenon should be recognized and reported to the referring healthcare providers and its clinical significance addressed as indicated.

Disposition of Work-Related Asthma in a Spanish Asthma Cohort: Comparison of Asthma Severity Between Employed and Retired Workers

Exposure to certain agents in the workplace can trigger occupational asthma or work-exacerbated asthma, both of which come under the heading of work-related asthma (WRA). Understanding the burden that WRA represents can help in the management of these patients. To assess the influence of occupation on asthma in real life and analyze the characteristics of patients with WRA included in an asthma cohort. This was a prospective multicenter study of a cohort of consecutive patients with asthma. A standardized clinical history was completed. Patients were classified as having WRA or non-WRA. All patients underwent respiratory function tests, FeNO test, and methacholine challenge (methacholine concentration that causes a 20% drop in FEV1) at the beginning of the study. They were classified into two groups, depending on their employment status: employed (group 1) or unemployed (group 2). Of the 480 patients included in the cohort, 82 (17%) received the diagnosis of WRA. Fifty-seven patients (70%) were still working. Mean age (SD) was 46 (10.69) years in group 1 and 57 (9.91) years in group 2 (P < .0001). Significant differences were observed in adherence to treatment (64.9% in group 1 vs 88% in group 2; P= .0354) and in severe asthma exacerbations (35.7% in group 1 vs 0% in group 2; P= .0172). No significant differences were observed in the rest of the variables analyzed. The burden of WRA in specialized asthma units is not negligible. The absence of differences in the severity of asthma, the treatment administered, alterations in lung function, and the number of exacerbations in those working versus not working may support the idea that advice regarding changing jobs should be customized for individual patients.

Bronchodilator Response in FEF25-75 for the Diagnosis of Asthma in Children.

Spirometry tests with a bronchodilator response (BDR) in FEV1, a methacholine concentration that produces a 20% drop in FEV1 (PC20) ≤ 2 mg/mL, and a positive exercise test have high specificity for the diagnosis of asthma in children. However, the value of forced expiratory flow during the middle half of the FVC maneuver (FEF25-75) in spirometry has been questioned. The objective of this study was to relate the BDR in FEF25-75 of spirometry tests with normal FEV1 and FEV1/FVC to airway hyper-responsiveness (AHR) to methacholine or exercise in children age 5-15 y with clinical suspicion of asthma. This was a cross-sectional study of spirometry tests performed between January 2017-December 2019 in children age 5-15 y with diagnostic suspicion of asthma who had a methacholine and/or exercise testing within a period not exceeding 60 d between exams. The mean (± SD) age of the children was 9.04 ± 2.67 y, with a range of 5-15 y, and 56.17% were male. Of the 324 spirometry tests with normal FEV1 and FEV1/FVC, 66 (20.4%) tests showed BDR in FEF25-75. A total of 46.9% and 33.3% of the children with and without BDR in FEF25-75, respectively, had a PC20 value ≤ 2 mg/mL and/or a positive exercise testing (P = .039). Children with suspected asthma and normal spirometry, other than BDR in FEF25-75, had greater AHR than those without BDR in FEF25-75. BDR in FEF25-75 was not always accompanied by AHR to confirm the diagnosis of asthma, so this study suggests that assessment of FEF25-75 alone is not always reliable for ruling in or ruling out AHR in the setting of otherwise normal spirometry results in children with suspected asthma.

The Effect of Zingiber cassumunar (Phlai Capsule) on Bronchial Hyperresponsiveness in Asthmatic Patients: A Randomized Controlled Trial

Background: Bronchial hyperresponsiveness (BHR) is a key feature of asthma. Compound D, an active compound in Phlai, can bind cysteinyl leukotrienes receptors that play a role for asthma treatment. Objective: To determine the effect of Phlai capsules on BHR measured by the methacholine challenge test. Materials and Methods: A randomized, double-blind, placebo-controlled, crossover study was conducted in adult asthmatic patients with partly controlled symptoms. Each patient received four weeks of treatment with either Phlai or placebo separated by a 2-week washout period. The main outcome was provocative concentration of methacholine causing a 20% drop in FEV₁ (PC₂₀). Asthma control test (ACT) scores, and fractional exhaled nitric oxide (FeNO) levels were secondary end points. Results: Thirty patients were randomly allocated to either the Phlai or the placebo group. All patients had allergic rhinitis and received inhaled corticosteroid and long-acting beta2-agonist (ICS/LABA) or ICS alone. Four weeks after treatment, mean PC₂₀ in the Phlai group was higher than in the placebo group at 9.76±1.56 mg/mL versus 6.05±1.65 mg/mL (p=0.151). The improvement of ACT scores in the Phlai group was significantly higher than in the placebo group. FeNO levels decreased after treatment in the Phlai group. All patients tolerated the treatment well and had no side effects. Conclusion: In adult asthmatic patients with partly controlled symptoms, concomitant treatment with Phlai capsules tended to decrease BHR and significantly improve symptom scores. Keywords: Asthma; Asthma control test; Bronchial hyperresponsiveness; Zingiber cassumunar; Phlai

Evaluation of asthma–chronic obstructive pulmonary disease overlap using a mouse model of pulmonary disease

BackgroundFeatures of asthma and chronic obstructive pulmonary disease (COPD) can coexist in the same patient, in a condition termed asthma– chronic obstructive pulmonary disease overlap (ACO). ACO is heterogeneous condition exhibiting various combinations of asthma and COPD features. No clinically acceptable experimental model of ACO has been established. We aimed to establish an animal model of ACO.MethodsWe generated two phenotypes of ACO by administering ovalbumin and porcine pancreatic elastase in combination, and papain. The proinflammatory cytokines and cell types in bronchoalveolar lavage fluid (BALF) were investigated, and lung function parameters were measured using the FlexiVent system.ResultsGreater airway inflammation was observed in the asthma and both ACO models, and emphysema was found in the COPD and both ACO models. The proportion of eosinophils in BALF was elevated in the asthma and ACO-a model. Type 2 inflammatory cytokine levels were highest in the ACO-a model, and the neutrophil gelatinase–associated lipocalin level was elevated in the asthma and ACO-a model. Of lung function parameters, compliance was greater in the COPD and ACO-b model, in which elastance was lower than in the asthma model. Airway resistance increased with the methacholine concentration in the asthma and both ACO models, but not in the control or COPD model.ConclusionWe established two murine models of ACO that exhibit features of asthma and COPD. We validated the clinical relevance of the ACO models based on changes in cytokine profiles and lung function. These models will be useful in further studies of the pathogenesis of, and therapeutic targets for ACO.

Development and validation of a predictive model combining patient-reported outcome measures, spirometry and exhaled nitric oxide fraction for asthma diagnosis.

Although asthma is a common disease, its diagnosis remains a challenge in clinical practice with both over- and underdiagnosis. Here, we performed a prospective observational study investigating the value of symptom intensity scales alone or combined with spirometry and exhaled nitric oxide fraction (F ENO) to aid in asthma diagnosis. Over a 38-month period we recruited 303 untreated patients complaining of symptoms suggestive of asthma (wheezing, dyspnoea, cough, sputum production and chest tightness). The whole cohort was split into a training cohort (n=166) for patients recruited during odd months and a validation cohort (n=137) for patients recruited during even months. Asthma was diagnosed either by a positive reversibility test (≥12% and ≥200 mL in forced expiratory volume in 1 s (FEV1)) and/or a positive bronchial challenge test (provocative concentration of methacholine causing a 20% fall in FEV1 ≤8 mg·mL-1). In order to assess the diagnostic performance of symptoms, spirometric indices and F ENO, we performed receiver operating characteristic curve analysis and multivariable logistic regression to identify the independent factors associated with asthma in the training cohort. Then, the derived predictive models were applied to the validation cohort. 63% of patients in the derivation cohort and 58% of patients in the validation cohort were diagnosed as being asthmatic. After logistic regression, wheezing was the only symptom to be significantly associated with asthma. Similarly, FEV1 (% pred), FEV1/forced vital capacity (%) and F ENO were significantly associated with asthma. A predictive model combining these four parameters yielded an area under the curve of 0.76 (95% CI 0.66-0.84) in the training cohort and 0.73 (95% CI 0.65-0.82) when applied to the validation cohort. Combining a wheezing intensity scale with spirometry and F ENO may help in improving asthma diagnosis accuracy in clinical practice.

The cumulative effect of methacholine on large and small airways when deep inspirations are avoided.

The effect of serial incremental concentrations of methacholine is only slightly cumulative when assessed by spirometry. This limited cumulative effect may be attributed to the bronchodilator effect of deep inspirations that are required between concentrations to measure lung function. Using oscillometry, the response to methacholine can be measured without deep inspirations. Conveniently, oscillometry can also dissociate the contribution of large versus small airways. Herein, oscillometry was used to assess the cumulative effect of methacholine in the absence of deep inspirations on large and small airways. Healthy and asthmatic volunteers underwent a multiple-concentration methacholine challenge on visit 1 and a single-concentration challenge on visit 2 using the highest concentration of visit 1. The maximal response was compared between visits to assess the cumulative effect of methacholine. The lung volume was also measured after the final concentration to assess hyperinflation. In both healthy and asthmatic subjects, increases in resistance at 19 Hz (Rrs19 ), reflecting large airway narrowing, did not differ between the multiple- and the single-concentration challenge. However, increases in resistance at 5Hz (Rrs5 ) minus Rrs19 , reflecting small airway narrowing, were 117 and 270% greater in the multiple- than the single-concentration challenge in healthy (p= 0.006) and asthmatic (p < 0.0001) subjects, respectively. Hyperinflation occurred with both challenges and was greater in the multiple- than the single-concentration challenge in both groups. Without deep inspirations, the effect of methacholine is cumulative on small airways but not on large airways. Lung hyperinflation and derecruitment may partially explain these different responses.

Long Term Pulmonary Effects of E‐cigarettes on in‐utero Exposed Mice

IntroductionThe in‐utero environment is delicate, as it fosters the proper health and growth of the fetus. Negative environmental effects during gestation increase the chances of long‐term developmental consequences. As e‐cigarettes gain popularity in pregnant mothers, the aim of this study is to observe the chronic pulmonary function of adult mice exposed to e‐cigarette vapor during gestation.MethodsPregnant mice underwent exposure for 4 hours a day, 5 days a week beginning from the first day of pairing for breeding and ending at birth. Mice were separated into three exposure groups each receiving one 70 mL e‐cig vapor puff per minute of (1) E‐cig vapor with nicotine Nic(+) (2% Nic 50:50 propylene glycol:vegetable glycerin), (2) E‐cig exposure without nicotine Nic(‐) (propylene glycol: vegetable glycerin), or (3) continuous filtered air exposure (FA)HEPA filter. Resulting pups from each group were examined at adulthood (4‐5 months). Data including baseline lung mechanic scan and a dose response to different concentrations of methacholine, a drug used to induce airway hyperreactivity, were obtained via the FlexiVent FX2 (SCIREQ Inc.)ResultsMale and female offspring of mice exposed to Nic(‐) and Nic(+) witnessed a significant decrease in overall lung function as compared to the FA group. Baseline compliance (Crs) was significantly decreased in the Nic(‐) female group and Nic(‐) and Nic(+) male groups (P &lt; 0.05 via ANOVA). Female and male mice in the Nic(‐) had greater stiffness (Ers) than the corresponding FA group (P &lt; 0.05). Upon addition of methacholine, female mice in the Nic(‐) and male mice in the Nic(+) had an increased amount of lung resistance (Rrs)upon inhalation (P &lt; 0.05). Female mice in the Nic(‐) had decreased forced expiratory volume (FEV0.1) in comparison with the FA group (P &lt; 0.05).ConclusionPreliminary data supports that in‐utero exposed mice to e‐cigarette vapor with or without nicotine causes long term alterations in lung function. Future directions aim to understand the mechanisms of change through observing changes in histology, altered gene expression, protein analysis, and epigenetic changes through DNA methylation. Results of this work demonstrate that vaping may not be a safe alternative to smoking during pregnancy as the health of the offspring have detrimental pulmonary effects in adulthood.

Wheeze is an unreliable endpoint for bronchial methacholine challenges in preschool children.

BackgroundOnset of wheeze is the endpoint often used in the determination of a positive bronchial challenge test (BCT) in young children who cannot perform spirometry. We sought to assess several clinical endpoints at the time of a positive BCT in young children with recurrent wheeze compared to findings in school‐aged children with asthma.MethodsPositive BCT was defined in: (1) preschool children (n = 22) as either persistent cough, wheeze, fall in oxygen saturation (SpO2) of ≥5%, or ≥50% increase in respiratory rate (RR) from baseline; and (2) school‐aged children (n = 22) as the concentration of methacholine (MCh) required to elicit a 20% decline in FEV1 (PC20).ResultsAll preschool children (mean age 3.4 years) had a positive BCT (median provocative MCh concentration 1.25 mg/ml [IQR, 0.62, 1.25]). Twenty (91%) school‐aged children (mean age 11.3 years) had a positive BCT (median PC20 1.25 mg/ml [IQR, 0.55, 2.5]). At the time of the positive BCT, the mean fall in SpO2 (6.9% vs. 3.8%; p = .001) and the mean % increase in RR (61% vs. 22%; p < .001) were greater among preschool‐aged than among school‐aged children. A minority of children developed wheeze at time of positive BCT (23% preschool‐ vs. 15% school‐aged children; p = .5).ConclusionsThe use of wheeze as an endpoint for BCT in preschool children is unreliable, as it rarely occurs. The use of clinical endpoints, such as ≥25% increase in RR or fall in SpO2 of ≥3%, captured all of our positive BCT in preschool children, while minimizing undue respiratory distress.

Anti–Interleukin-5 Therapy Is Associated with Attenuated Lung Function Decline in Severe Eosinophilic Asthma Patients From the Belgian Severe Asthma Registry

Asthmatics have accelerated lung function decline over time compared with healthy individuals. To evaluate risk factors for accelerated lung function decline. In a longitudinal analysis on severe asthmatics enrolled in the Belgian Severe Asthma Registry with at least 2 visits a minimum of 12 months apart, we compared characteristics of patients with and without decline (loss of post-bronchodilation forced expiratory volume in 1 s [FEV1] (% predicted)/y greater than zero) over time. Multiple linear regression was applied to study the factors independently associated with FEV1 decline. In the overall population (n= 318), median annual FEV1 decline was 0.27 (-4.22 to 3.80) % predicted/y over a period of 23 months (12-41 months). Asthma was less controlled at baseline in nondecliners than in decliners (53%). Lung function and residual volume at baseline were higher in the declining group. Decliners presented with increased bronchial reactivity (ie, a lower provocative concentration of methacholine causing a 20% fall in FEV1) at baseline. Twenty-five percent of nondecliners were started on anti-interleukin-5 (anti-IL-5) for severe eosinophilic asthma during the study compared with 10% of decliners. The multivariable model suggested that Asthma Control Questionnaire score at baseline, late-onset asthma, and addition of anti-IL-5 during follow-up were associated with lower FEV1 decline, independently from other variables such as evolution in exacerbations, smoking status, inhaled corticosteroids or oral corticosteroids dose, or add-on anti-immunoglobulin E over time, whereas reversibility to salbutamol and higher FEV1 were associated with accelerated FEV1 decline. Add-on therapy with anti-IL-5 in severe eosinophilic asthma was associated with an attenuated FEV1 decline. The causality of this observation should, however, be confirmed in future prospective controlled studies.

Methacholine challenges: comparison of different tidal breathing challenge methods.

Tidal-breathing methacholine challenges are now recommended by guidelines, to avoid the bronchoprotective effects of deep inhalation. This study compared different tidal breathing methacholine challenge methods; assessed the agreement between tidal dosimetric and continuous output challenges; and assessed challenge repeatability with different methods.15 asthma patients performed dosimetric challenges and a continuous-output breath-actuated challenge, all ≥3 days apart. All subjects had a pre-bronchodilator forced expiratory volume in 1 s (FEV1) ≥65% predicted, and a cumulative dose causing a 20% reduction in FEV1 (PD20) <1.2 mg.Of the dosimetric challenges, one method increased methacholine concentration (standard dosimetric challenge), and one adjusted nebuliser output time to increase dose (adjusted dosimetric challenge). The adjusted dosimetric and continuous output challenges were performed twice on separate days to assess for repeatability. All challenges were matched for dose at each dose step. The mean PD20 ratio of the standard dosimetric challenge to the adjusted dosimetric challenge was 0.90 (95% CI 0.66–1.23, p=0.49) and intraclass correlation coefficient (ICC) was 0.82. Repeated adjusted dosimetric challenges had an ICC 0.62 for PD20. Repeated continuous output challenges had an ICC 0.74 for PD20. The adjusted dosimetric and continuous output challenges correlated (r=0.69, p=0.0043; ICC 0.65), but PD20 was higher for the adjusted dosimetric challenge (mean PD20 ratio 2.31, 95% CI 1.57–3.40; p=0.0004).Tidal dosimetric methacholine challenge using adjustment of nebuliser output produces results with good repeatability. The results of this adjusted dosimetric method differed from the continuous output method, underscoring that the results of different methacholine challenge methodologies may not be directly comparable.

A safe and effective mucosal RSV vaccine in mice consisting of RSV phosphoprotein and flagellin variant.

Respiratory syncytial virus (RSV) is a major cause of serious acute lower respiratory tract infection in infants and the elderly. The lack of a licensed RSV vaccine calls for the development of vaccines with other targets and vaccination strategies. Here, we construct a recombinant protein, designated P-KFD1, comprising RSV phosphoprotein (P) and the E.-coli-K12-strain-derived flagellin variant KFD1. Intranasal immunization with P-KFD1 inhibits RSV replication in the upper and lower respiratory tract and protects mice against lung disease without vaccine-enhanced disease (VED). The P-specific CD4+ Tcells provoked by P-KFD1 intranasal (i.n.) immunization either reside in or migrate to the respiratory tract and mediate protection against RSV infection. Single-cell RNA sequencing (scRNA-seq) and carboxyfluorescein succinimidyl ester (CFSE)-labeled cell transfer further characterize the Th1 and Th17 responses induced by P-KFD1. Finally, we find that anti-viral protection depends on either interferon-γ (IFN-γ) or interleukin-17A (IL-17A). Collectively, P-KFD1 is a promising safe and effective mucosal vaccine candidate for the prevention of RSV infection.

Nitrite supplementation preserves aortic endothelial‐dependent vasodilation in chronically stressed mice

Chronic stress increases the risk of developing cardiovascular disease potentially via endothelial dysfunction. Decreased bioavailability of the potent vasodilator nitric oxide (NO) describes a hallmark of endothelial dysfunction. Nitrite (NO2-) reduces into active NO, providing an alternative pathway of NO restoration. The effect of nitrite supplementation on aortic endothelial function has yet to be determined in chronically stressed mice. We hypothesized that nitrite supplementation would rescue chronic stress-attributed impairments in aortic endothelial function. Male and female C57Bl/6 mice at 18 weeks-of-age underwent an unpredictable chronic mild stress (UCMS; 5 days/week for 7 hrs/day) paradigm to elicit a chronically stressed phenotype. Control and stressed mice underwent 8 weeks of NO2- supplementation (50mg/L) within their drinking water. At 26 weeks, mice were euthanized, and the thoracic aortas were removed and positioned in a wire myograph chamber. To assess vessel health, the aortas were precontracted with U46619 (7.5x10-9M) and exposed to increasing concentrations of methacholine (MCh; 10-9M to 10-5M) and sodium nitroprusside (SNP; 10-9M to 10-5M). Maximal aorta dilation to MCh was impaired in UCMS mice vs. controls (71±3% vs 87±1%; p<0.05). However, chronic NO2- supplementation prevented the impairment in aortic dilation with UCMS (83±2% vs 71±3%; p<0.05). Maximal aorta dilation to SNP was not affected by UCMS and or NO2- supplementation, with normal aortic smooth muscle dilation. In conclusion, these data suggest an impairment in aortic endothelial function due to chronic stress that is prevented with chronic NO2- supplementation.

The Evaluation of Acute Lung Injury Induced by Nitrogen Mustard in Mouse Precision Cut Lung Slices

Nitrogen Mustard (NM; mechlorethamine hydrochloride) is a cytotoxic alkylating agent known to cause progressive pulmonary injury. Its toxic properties elicit extensive tissue remodeling within the respiratory tract, contributing to the development of chronic lung disease. Precision-Cut Lung Slices (PCLS) represent an ex vivo alternative to in vivo studies, minimizing animal numbers while increasing experimental replicates, which is advantageous for mechanistic toxicology studies and evaluating potential therapeutics. PCLS are three-dimensional excerpts of the lung that include all resident cell types; they remain viable in culture for up to 14 days, allowing for evaluation of functional activity, structural alterations and cytotoxicity. In the present studies, PCLS were used to assess NM-induced lung injury and alterations in pulmonary mechanics. C57BL/6 mice were euthanized, the lungs filled with agarose, isolated after congealment, and sliced (300 mM in thickness); slices were cultured in Dulbecco's Modified Eagle's Medium (DMEM) and Ham's F-12 Nutrient Mixture (DMEM/F-12). Twenty-four hours later, PCLS were treated with NM (1, 10, and 100 mM) for one hour, washed, refed with medium and cultured for 3 days. NM caused a dose-related increase in cytotoxicity and a decrease in mitochondrial activity as measured by lactate dehydrogenase (LDH) and WST-1 assays, respectively. Analysis of histologic sections revealed that NM caused damage to the airway epithelium; this was associated with decreased mRNA expression of collagen1A1 and collagen3A1, markers of tissue repair. To determine if these changes were linked to altered pulmonary function, we measured airway responsiveness using video microscopy. In these studies, changes in airway area after stimulation with increasing concentrations of methacholine were assessed in cross-sectional airways. Consistent with structural alterations, NM caused a ~30% decrease in maximal airway contraction after methacholine, relative to control, indicating a loss in airway smooth muscle function. These data demonstrate that PCLS can be used effectively to mechanistically assess the progression of injury induced by NM. Further understanding of the progression of damage and repair processes following exposure to mustards is essential in order to develop therapeutics for treating pulmonary toxicity.

Current Asthma Prevalence Using Methacholine Challenge Test in Korean Children from 2010 to 2014.

BackgroundMost epidemiological studies depend on the subjects' response to asthma symptom questionnaires. Questionnaire-based study for childhood asthma prevalence may overestimate the true prevalence. The aim of this study was to investigate the prevalence of “Current asthma” using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire and methacholine challenge test in Korean children.MethodsOur survey on allergic disease included 4,791 children (age 7–12 years) from 2010 to 2014 in Korean elementary schools. Bronchial hyperresponsiveness (BHR) was defined as provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second (FEV1) (PC20) ≤ 16 mg/mL. “Current asthma symptoms” was defined as positive response to “Wheezing, current,” “Treatment, current,” or “Exercise, current.” “Current asthma” was defined when the subjects with “Current asthma symptoms” showed BHR on the methacholine challenge test or had less than 70% of predicted FEV1 value.ResultsThe prevalence of “Wheezing, ever,” “Wheezing, current,” “Diagnosis, ever,” “Treatment, current,” “Exercise, current,” and “Current asthma symptoms” was 19.6%, 6.9%, 10.0%, 3.3%, 3.5%, and 9.6%, respectively, in our cross-sectional study of Korean elementary school students. The prevalence of BHR in elementary school students was 14.5%. The prevalence of BHR in children with “Wheezing, ever,” “Wheezing, current,” “Diagnosis, ever,” “Treatment, current,” and “Exercise, current” was 22.3%, 30.5%, 22.4%, 28.8%, and 29.9%, respectively. BHR was 26.1% in those with “Current asthma symptoms.” The prevalence of “Current asthma” was 2.7%.ConclusionsOur large-scale study provides 2.7% prevalence of current asthma in Korean elementary school children. Since approximately one third of the children who have “Current asthma symptoms” present BHR, both subjective and objective methods are required to accurately predict asthma in subjects with asthma symptoms.

Analysis of PC20-FEF25%–75% and ΔFVC in the methacholine bronchial provocation test

Purpose: Forced expiratory flow between 25% and 75% (FEF25%-75%) is known to sensitively reflect bronchial obstruction. Methacho line challenge test (MCT) has shown varying reduction levels of forced vital capacity (FVC) with the reduction in forced expiratory volume in 1 second (FEV1) in asthma. The aim of this study was to evaluate the clinical implication of provocative concentration causing a 20% fall in FEF25%-75% (PC20-FEF25%-75%) and the percentage fall in FVC at the PC20 dose of methacholine (△FVC). Methods: A total of 194 children who visited the hospital due to respiratory symptoms and underwent MCT were analyzed retro spectively. The patients were divided into 3 groups. Group I had both PC20-FEV1 and PC20-FEF25%-75% above 16 mg/mL; group II had a PC20-FEF25%-75% that fell below 16 mg/mL but PC20-FEV1 was 16 mg/mL or above; group III had a PC20-FEV1 and a PC20-FEF25%-75% that both fell below 16 mg/mL. Results: In group II, PC20-FEV1 was lower (P=0.026) and the rate of change in FEV1 and FEF25%-75% from baseline to 16 mg/mL of methacholine concentration was greater than in group I (both P<0.001). Levels of PC20-FEF25%-75% were higher in group II compared to group III (P<0.001). △FVC showed a correlation with PC20-FEV1 (P<0.001) only in the whole group. Conclusion: In asthmatic children, PC20-FEF25%-75% may be associated with bronchial hyperresponsiveness. △FVC was not associated with other parameters in either group. For subjects with a positive finding of PC20-FEF25%-75% and a negative finding of MCT, the pro gression to asthma can be suspected. (Allergy Asthma Respir Dis 2021;9:141-147)

Evaluation of Fractional Exhaled Nitric Oxide in Pediatric Asthma and Allergic Rhinitis.

Fractional exhaled nitric oxide (FeNO) is a non-invasive test for evaluating the degree of airway inflammation and for the diagnosis, evaluation, and treatment of asthma. We attempted to measure FeNO levels in Korean children with asthma and determine its cutoff value for diagnosing asthma. We enrolled 176 children and adolescents between the ages of 5 and 18 years, who visited for the evaluation of chronic cough, shortness of breath, and wheezing. Among them, 138 patients who underwent skin prick tests or inhalation Immuno CAP (UniCAP; Pharmacia, Uppsala, Sweden) tests for allergy testing together with a pulmonary function test were included. FeNO was measured using a NIOX MINO (Aerocrine AB, Solna, Sweden) instrument according to the American Thoracic Society/European Respiratory Society (ATS/ERS) guidelines. There were 29 patients with asthma, 43 with rhinitis, and 38 with asthma and allergic rhinitis. In the asthma group, FeNO levels significantly correlated with total immunoglobulin E (r = 0.572, p < 0.001), but did not show significant correlation with pulmonary function test parameters (forced vital capacity—FVC, forced expiratory volume in one second—FEV1, FEV1/FVC) or PC20 (provocative concentration of methacholine causing a 20% fall in FEV1). The FeNO cutoff values obtained in the asthma and asthma rhinitis groups were 16.5 ppb and 18.5 ppb, respectively. Hence, we provide a FeNO cutoff value according to the presence or absence of rhinitis in pediatric patients with asthma.

Eosinophil microRNAs Play a Regulatory Role in Allergic Diseases Included in the Atopic March.

(1) Background: The atopic march is defined by the increased prevalence of allergic diseases after atopic dermatitis onset. In fact, atopic dermatitis is believed to play an important role in allergen sensitization via the damaged skin barrier, leading to allergic diseases such as allergic asthma and allergic rhinitis. The eosinophil, a pro-inflammatory cell that contributes to epithelial damage, is one of the various cells recruited in the inflammatory reactions characterizing these diseases. Few studies were conducted on the transcriptome of this cell type and even less on their specific microRNA (miRNA) profile, which could modulate pathogenesis of allergic diseases and clinical manifestations post-transcriptionally. Actually, their implication in allergic diseases is not fully understood, but they are believed to play a role in inflammation-related patterns and epithelial cell proliferation. (2) Methods: Next-generation sequencing was performed on RNA samples from eosinophils of individuals with atopic dermatitis, atopy, allergic rhinitis and asthma to obtain differential counts of primary miRNA (pri-miRNA); these were also analyzed for asthma-related phenotypes such as forced expiratory volume in one second (FEV1), immunoglobulin E (IgE) and provocative concentration of methacholine inducing a 20% fall in forced expiratory volume in 1 s (PC20) levels, as well as FEV1 to forced vital capacity (FEV1/FVC) ratio. (3) Results: Eighteen miRNAs from eosinophils were identified to be significantly different between affected individuals and unaffected ones. Based on counts from these miRNAs, individuals were then clustered into groups using Ward’s method on Euclidian distances. Groups were found to be explained by asthma diagnosis, familial history of respiratory diseases and allergic rhinitis as well as neutrophil counts. (4) Conclusions: The 18 differential miRNA counts for the studying phenotypes allow a better understanding of the epigenetic mechanisms underlying the development of the allergic diseases included in the atopic march.