Dyspnea and asthma

β-Elemene in zedoary turmeric oil injection induces dyspnea by binding to hemoglobin and upregulating HIF-1α

ETHNOPHARMACOLOGICAL RELEVANCE

Zedoary turmeric oil injection (ZTOI) extracted from the rhizome extract of Curcuma phaeocaulis Valeton, Curcuma wenyujin Y. H. Chen et C. Ling or Curcuma kwangsiensis S. G. Lee et C. F. Liang, is widely used for the treatment of virus-induced upper respiratory tract infections, peptic ulcers, viral pneumonia, etc. However, it has attracted widespread attention because it often causes adverse drug reactions (ADRs), including dyspnea. However, little is known about the mechanism underlying dyspnea caused by ZTOI, which limits its clinical application.

AIM OF THE STUDY

To investigate the major pathophysiologic signatures and underlying mechanism of ZTOI-related dyspnea.

METHODS

Respiratory function detection was used to explore the pathophysiologic signature of dyspnea induced by ZTOI. UV-vis absorption spectroscopy and isothermal titration calorimetry were applied to test the interaction between ZTOI and hemoglobin (Hb). GC‒MS was used to identify the main components in ZTOI. Molecular docking, surface plasmon resonance, and circular dichroism spectroscopy were employed to test the reaction between β-elemene and Hb. Western blot was performed to investigate the effect of β-elemene on the hypoxia signaling pathway.

RESULTS

The results showed that ZTOI-induced dyspnea was related to a decreased oxygen carrying capacity of Hb. The molecular interaction between ZTOI and Hb was proven. Notably, β-elemene in ZTOI exhibited high binding affinity to Hb and altered its secondary structure. Furthermore, it was found that β-elemene downregulated the expression of prolyl hydroxylase-domain protein 2 and upregulated the expression of hypoxia-inducible factor-1α.

CONCLUSIONS

Our study is valuable for better understanding the pathophysiological characteristics and underlying mechanism of ZTOI to ensure its safe clinical application. We also provided a strategy to elucidate the underlying mechanism based on inspiration from clinical ADR phenotypes for investigating other medical products with ADRs in the clinic.

Upper Airway-Related Symptoms According to Mental Illness and Sleep Disorders among Workers Employed by a Large Non-Profit Organization in the Mountain West Region of the United States

The relationships between selected upper airway-related symptoms (speech disturbances, voice disorders, cough, and breathing abnormalities) and mental illness and sleep disorders have been previously demonstrated. However, these relationships have not been compared in a single study with consideration of potential confounding variables. The current research incorporates a descriptive study design of medical claims data for employees (~21,362 per year 2017-2021) with corporate insurance to evaluate the strength of these relationships, adjusting for demographic variables and other important confounders. The upper airway-related symptoms are each significantly and positively associated with several mental illnesses and sleep disorders, after adjusting for demographic and other potential confounders. The rate of any mental illness is 138% (95% CI 93-195%) higher for speech disturbances, 55% (95% CI 28-88%) higher for voice disorders, 28% (95% CI 22-34%) higher for cough, and 58% (95% CI 50-66%) higher for breathing abnormalities, after adjustment for the confounding variables. Confounding had significant effects on the rate ratios involving cough and breathing abnormalities. The rate of any sleep disorder is 78% (95% CI 34-136%) higher for speech disturbances, 52% (95% CI 21-89%) higher for voice disorders, 34% (95% CI 27-41%) higher for cough, and 172% (95% CI 161-184%) higher for breathing abnormalities, after adjustment for the confounding variables. Confounding had significant effects on each of the upper airway-related symptoms. Rates of mental illness and sleep disorders are positively associated with the number of claims filed for each of the upper airway-related symptoms. The comorbid nature of these conditions should guide clinicians in providing more effective treatment plans that ultimately yield the best outcome for patients.

Exosomal circCLIP1 regulates PM2.5-induced airway obstruction via targeting SEPT10 in vitro

Fine particulate matter (PM_2.5) exposure correlates with airway obstruction, but the mechanism remains to be fully elucidated. We aim to investigate the role of exosomal circular RNAs (circRNAs)-mediated communication between airway epithelial cells and airway smooth muscle cells in PM_2.5-induced airway obstruction. RNA sequencing revealed that acute PM_2.5 exposure altered the expression profiles of 2904 exosomal circRNAs. Among them, exosomal hsa_circ_0029069 (spliced from CLIP1, thus termed circCLIP1 hereafter) with a loop structure was upregulated by PM_2.5 exposure and mainly encapsulated in exosomes. Then, the biological functions and the underlying mechanisms were explored by Western blot, RNA immunoprecipitation and RNA pull-down, etc. Phenotypically, exosomal circCLIP1 entered recipient cells, inducing mucus secretion in recipient HBE cells and contractility of sensitive HBSMCs. Mechanistically, circCLIP1 was upregulated by METTL3-mediated N⁶-methyladenine (m⁶A) modification in PM_2.5-treated producer HBE cells and exosomes, then enhancing the expression of SEPT10 in recipient HBE cells and sensitive HBSMCs. Our study revealed that exosomal circCLIP1 played a critical role in PM_2.5-induced airway obstruction and provided a new potential biomarker for the assessment of PM_2.5-related adverse effects.

Mechanisms underlying the sensation of dyspnea

Dyspnea is defined as a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity. It is a common symptom among patients with respiratory diseases that reduces daily activities, induces deconditioning, and is self-perpetuating. Although clinical interventions are needed to reduce dyspnea, its underlying mechanism is poorly understood depending on the intertwined peripheral and central neural mechanisms as well as emotional factors. Nonetheless, experimental and clinical observations suggest that dyspnea results from dissociation or a mismatch between the intended respiratory motor output set caused by the respiratory neuronal network in the lower brainstem and the ventilatory output accomplished. The brain regions responsible for detecting the mismatch between the two are not established. The mechanism underlying the transmission of neural signals for dyspnea to higher sensory brain centers is not known. Further, information from central and peripheral chemoreceptors that control the milieu of body fluids is summated at higher brain centers, which modify dyspneic sensations. The mental status also affects the sensitivity to and the threshold of dyspnea perception. The currently used methods for relieving dyspnea are not necessarily fully effective. The search for more effective therapy requires further insights into the pathophysiology of dyspnea.

Symptoms and perception of airway obstruction in asthmatic patients: Clinical implications for use of reliever medications

BACKGROUND

Asthma causes the unpleasant sensation of breathlessness (dyspnea) caused by airway obstruction. Patients with poor perception of airway obstruction are at risk of delay in seeking medical attention and undertreatment, which can lead to avoidable deaths. Conversely, those with heightened perception are at risk of overtreatment and iatrogenic adverse effects with reliever medications, anxiety, and unnecessary use of health care resources.

OBJECTIVE

We sought to review evidence about symptom misperception in asthmatic patients and how to identify and manage affected patients, particularly with regard to reliever medications.

METHODS

We conducted a systematic literature search for studies of perception of airway function in asthmatic patients. We searched the OVID (Medline and Medline [R] in process [PubMed]), Embase, and Adisearch/Odyssey databases, restricting our search to human studies published in English from 1990-2018, with no restrictions on age, sex, or racial origin.

RESULTS

We found that both underperception and overperception assessed during induced bronchoconstriction or bronchodilation or during changes in airway resistance were common across all age groups and that aging, disease severity, smoking, sex, ethnicity, psychologic factors, and medication are all associated with differences in perception. Importantly, airway inflammation was associated with impaired perception and a history of severe or near-fatal asthma. We also identified knowledge gaps, such as whether an individual patient's perception varies over time and the influence perception has on patients' use of reliever medication.

CONCLUSION

We found that abnormal perception of airway obstruction has important clinical implications for the management of patients with asthma.

Hypoxia and Redox Signaling on Extracellular Matrix Remodeling: From Mechanisms to Pathological Implications

SIGNIFICANCE

The extracellular matrix (ECM) is an essential modulator of cell behavior that influences tissue organization. It has a strong relevance in homeostasis and translational implications for human disease. In addition to ECM structural proteins, matricellular proteins are important regulators of the ECM that are involved in a myriad of different pathologies. Recent Advances: Biochemical studies, animal models, and study of human diseases have contributed to the knowledge of molecular mechanisms involved in remodeling of the ECM, both in homeostasis and disease. Some of them might help in the development of new therapeutic strategies. This review aims to review what is known about some of the most studied matricellular proteins and their regulation by hypoxia and redox signaling, as well as the pathological implications of such regulation.

CRITICAL ISSUES

Matricellular proteins have complex regulatory functions and are modulated by hypoxia and redox signaling through diverse mechanisms, in some cases with controversial effects that can be cell or tissue specific and context dependent. Therefore, a better understanding of these regulatory processes would be of great benefit and will open new avenues of considerable therapeutic potential.

FUTURE DIRECTIONS

Characterizing the specific molecular mechanisms that modulate matricellular proteins in pathological processes that involve hypoxia and redox signaling warrants additional consideration to harness the potential therapeutic value of these regulatory proteins. Antioxid. Redox Signal. 27, 802-822.

Risk of bipolar disorder in patients with COPD: a population-based cohort study

BAKCGROUND

Few studies have investigated the relationship between chronic obstructive pulmonary disease (COPD) and bipolar outcomes in the world. We sought to investigate the association between COPD and risk of bipolar disorder in a large national sample.

METHODS

The insured aged 15 years or more with a new primary diagnosis of COPD (ICD-9: 491, 492, 494 and 496) between 2000 and 2007 were identified from Taiwan's National Health Insurance Research Database. We included individuals with an inpatient diagnosis of COPD and/or at least 1 year of two diagnoses of COPD in outpatient services. These 35,558 cases were compared to 35,558 sex-, age-, residence- and insurance premium-matched controls. We followed both groups until the end of 2008 for incidence of bipolar disorder, defined as ICD-9 codes 296.0-296.16, 296.4-296.81 and 296.89. Competing risk-adjusted Cox regression analyses were applied with adjusting for sex, age, residence, insurance premium, prednisone use, Charlson comorbidity index, diabetes, hypertension, hyperlipidemia, cardiovascular diseases, hospital admission days, outpatients' visits and mortality.

RESULTS

Of the total 71,116 subjects, 202 were newly diagnosed with bipolar disorder during the study period. The mean follow-up time was 6.0 (SD=2.2) years. COPD, younger age, lower economic status, lower dose of prednisone use, higher hospital admission days and higher outpatient visits were independent predictors of bipolar disorder.

CONCLUSIONS

COPD was associated with increased risk of bipolar disorder independent of a number of potential confounding factors in this study.

Clinically relevant outcome measures for new therapies of asthma using pharmaceutical and biologic agents

PURPOSE OF REVIEW

To determine the benefits of new asthma drugs or therapies, they should be assessed with regard to their effects on relevant clinical outcomes.

RECENT FINDINGS

The most frequently used outcomes have been symptoms, rescue medication needs and pulmonary function tests, although others such as quality of life, exacerbations and impairment of activities have also been identified as important ones. Improvements in our understanding of basic mechanisms of asthma have led to the development of new sets of outcomes including inflammatory markers and a rapidly increasing number of biomarkers, which however require validation, and assessment of their clinical usefulness. Many studies have not only looked at induced sputum cell differentials or FENO to phenotype asthma but also as treatment efficacy markers. Periostin is considered a marker of TH2-induced airway inflammation and a predictor of response to drugs such as anti-IL13 and omalizumab, although at the individual level, such prediction remains imperfect.

SUMMARY

There is a need to develop new markers of activity of the disease, with a prognostic value with regard to the benefits of new treatments.

Glucocorticoids and the Lung

The lung is a major clinical target of glucocorticoid-based therapeutics, and GR signaling has broad effects on respiratory physiology and inflammation. During lung development, expression of GR in the mesenchyme is required for normal terminal alveolar epithelial differentiation. Prenatal administration of exogenous glucocorticoids (GCs) to prevent neonatal respiratory distress syndrome, however, promotes alveolar maturation and accelerates surfactant expression in a manner consistent with direct effects on the developing alveolar epithelium. Likewise, cell autonomous effects of GCs in regulating gene expression and phenotype of the airway epithelium and airway smooth muscle have been demonstrated to control important therapeutic effects of GCs in treating asthma and chronic obstructive pulmonary disease. Here, mechanisms and consequences of GR signaling in the developing lung and in treating obstructive lung disease are reviewed, with a focus on direct effects of GR signaling on alveolar differentiation, surfactant expression, and airway epithelial and smooth muscle pathophysiology.

Understanding health beliefs and behaviour in workers with suspected occupational asthma

INTRODUCTION

Long delays from symptom onset to the diagnosis of occupational asthma have been reported in the UK, Europe and Canada and workers are often reluctant to seek medical help or workplace solutions for their symptoms. Reducing this delay could improve workers' quality of life, and reduce the societal cost of occupational asthma. This study aimed to explore reasons behind such delays.

METHODS

A purposive sample of 20 individuals diagnosed with, or under investigation for, occupational asthma (median age = 52; 70% male; 80% white British) undertook a single semi-structured interview. Interviews were transcribed verbatim and thematic analysis was undertaken in order to explore health beliefs and identify barriers to diagnosis.

RESULTS

Four themes were identified: (1) workers' understanding of symptoms, (2) working relationships, (3) workers' course of action and (4) workers' negotiation with healthcare professionals. Understanding of symptoms varied between individuals, from a lack of insight into the onset, pattern and nature of symptoms, through to misunderstanding of what they represented, or ignorance of the existence of asthma as a disease entity. Workers described reluctance to discuss health issues with managers and peers, through fear of job loss and a perceived lack of ability to find a solution. The evolution of workers' understanding depended upon how actively they looked to define symptoms or seek a solution. Proactive workers were motivated to seek authoritative help and negotiate inadequate healthcare encounters with GPs.

CONCLUSION

Understanding workers' health beliefs will enable policy makers and clinicians to develop better workplace interventions that may aid diagnosis and reduce delay in identifying occupational asthma.

Overweight children report qualitatively distinct asthma symptoms: analysis of validated symptom measures

BACKGROUND

Past studies of asthma in overweight/obese children have been inconsistent. The reason overweight/obese children commonly report worse asthma control remains unclear.

OBJECTIVE

To determine qualitative differences in symptoms between lean and overweight/obese children with early-onset, atopic asthma.

METHODS

We conducted a cross-sectional analytic study of lean (20% to 65% body mass index) and overweight/obese (≥85% body mass index) 10- to 17-year-old children with persistent, early-onset asthma. Participants completed 2 to 3 visits to provide a complete history, qualitative and quantitative asthma symptom characterization, and lung function testing. We determined associations between weight status and symptoms using multivariable linear and logistic regression methods.

RESULTS

Overweight/obese and lean asthmatic children displayed similar lung function. Despite lower fraction of exhaled nitric oxide (30.0 vs 62.6 ppb; P = .037) and reduced methacholine responsiveness (PC20FEV1 1.87 vs 0.45 mg/mL; P < .012), overweight/obese children reported more than thrice frequent rescue treatments (3.7 vs 1.1 treatments/wk; P = .0002) than did lean children. Weight status affected the child's primary symptom reported with loss of asthma control (Fisher exact test; P = .003); overweight/obese children more often reported shortness of breath (odds ratio = 11.8; 95% CI, 1.41-98.7) and less often reported cough (odds ratio = 0.26; 95% CI, 0.08-0.82). Gastroesophageal reflux scores were higher in overweight/obese children (9.6 vs 23.2; P = .003) and appear to mediate overweight/obesity-related asthma symptoms.

CONCLUSIONS

Overweight/obese children with early-onset asthma display poorer asthma control and a distinct pattern of symptoms. Greater shortness of breath and β-agonist use appears to be partially mediated via esophageal reflux symptoms. Overweight children with asthma may falsely attribute exertional dyspnea and esophageal reflux to asthma, leading to excess rescue medication use.

Peripheral erythrocytes decrease upon specific respiratory challenge with grass pollen allergen in sensitized mice and in human subjects

BACKGROUND AND AIMS

Specific hyper-responsiveness towards an allergen and non-specific airway hyperreactivity both impair quality of life in patients with respiratory allergic diseases. We aimed to investigate cellular responses following specific and non-specific airway challenges locally and systemically in i) sensitized BALB/c mice challenged with grass pollen allergen Phl p 5, and in ii) grass pollen sensitized allergic rhinitis subjects undergoing specific airway challenge in the Vienna Challenge Chamber (VCC).

METHODS AND RESULTS

BALB/c mice (n = 20) were intraperitoneally immunized with grass pollen allergen Phl p 5 and afterwards aerosol challenged with either the specific allergen Phl p 5 (n = 10) or the non-specific antigen ovalbumin (OVA) (n = 10). A protocol for inducing allergic asthma as well as allergic rhinitis, according to the united airway concept, was used. Both groups of exposed mice showed significantly reduced physical activity after airway challenge. Specific airway challenge further resulted in goblet cell hyperplasia, enhanced mucous secretion, intrapulmonary leukocyte infiltration and lymphoid follicle formation, associated with significant expression of IL-4, IL-5 and IL-13 in splenocytes and also partially in lung tissue. Concerning circulating blood cell dynamics, we observed a significant drop of erythrocyte counts, hemoglobin and hematocrit levels in both mouse groups, challenged with allergen or OVA. A significant decrease in circulating erythrocytes and hematocrit levels after airway challenges with grass pollen allergen was also found in grass pollen sensitized human rhinitis subjects (n = 42) at the VCC. The effects on peripheral leukocyte counts in mice and humans however were opposed, possibly due to the different primary inflammation sites.

CONCLUSION

Our data revealed that, besides significant leukocyte dynamics, particularly erythrocytes are involved in acute hypersensitivity reactions to respiratory allergens. A rapid recruitment of erythrocytes to the lungs to compensate for hypoxia is a possible explanation for these findings.

Tidal volume inflection and its sensory consequences during exercise in patients with stable asthma

Sixteen patients with stable asthma performed a symptom-limited constant work-rate CWR cycle exercise during which breathing pattern, operating lung volumes, dyspnea intensity and its qualitative descriptors were measured. An inflection in the relation between tidal volume (V(T)) and ventilation (V˙(E)) was observed in each subject. The sense of "work/effort" was the dominant dyspnea descriptor selected up to the V(T)/V˙(E) inflection, whereas after it dyspnea intensity and the selection frequency of "unsatisfied inspiration" rose steeply in 37.5% of subjects in whom inspiratory reserve volume (IRV) had decreased to a critical level of 0.6L at the V(T) inflection point. In contrast, dyspnea increased linearly with exercise time and V˙(E), and "work/effort" was the dominant descriptor selected throughout exercise in 62.5% of subjects in whom the V(T)/V˙(E) inflection occurred at a preserved IRV. The V(T) inflection during exercise in patients with stable asthma marked a mechanical event with important sensory consequences only when it occurred at a critical reduced IRV.

Frequency of asthma as the cause of dyspnea in pregnancy

OBJECTIVE

To estimate the prevalence of asthma among pregnant women with dyspnea.

METHODS

Pregnant women referred for prenatal care visits who had complaints of dyspnea were included. All pregnant women were evaluated by a respiratory specialist. Spirometry was performed by a single trained physician.

RESULTS

Asthma was diagnosed in 38.8% of participants. Dyspnea was diagnosed as being physiologic in 36.4% of cases, but 24.8% of cases were of probable asthma (spirometric values were within normal range but symptoms and signs were suggestive of asthma). Cough, wheezing, and post-exercise symptoms were significantly more prevalent in asthmatic and probable-asthmatic women than in women without asthma.

CONCLUSION

Dyspnea in pregnancy can be physiologic, but when it is accompanied by other symptoms such as cough or wheezing it is likely to be caused by asthma. Because of the high prevalence of asthma during pregnancy, it seems logical to evaluate dyspnea via physical examination and response to bronchodilators.

Asthma morbidity among children evaluated by asthma case detection

OBJECTIVE

Population-based asthma detection is a potential strategy to reduce asthma morbidity in children; however, the burden of respiratory symptoms and health care use among children identified by case detection is not well known.

METHODS

Data come from a school-based asthma case detection validation study of 3539 children. Respiratory symptoms, emergency department (ED) visits, and hospitalizations were assessed by questionnaire for children whose case detection result and physician study diagnosis agreed.

RESULTS

Physician evaluation of 530 case detection results yielded 420 cases of agreement (168 children with previously diagnosed asthma, 39 with undiagnosed asthma, and 213 without asthma). Children with previously diagnosed asthma were more likely to be male (P < .0001). No differences in severity were observed in children with previously and undiagnosed asthma (P = .31). Children with undiagnosed asthma reported less frequent daytime and nighttime symptoms than children with previously diagnosed asthma but more than those without asthma (P < .0001). The proportion of children with at least 1 respiratory-related ED visit in the past year was 32%, 3%, and 3% for those with previously diagnosed, undiagnosed, and no asthma, respectively (P < .0001). The proportion with at least 1 respiratory-related hospitalization was 8%, 0%, and 0%, respectively (P < .0001). There were no differences in nonrespiratory ED visits (P = .93).

CONCLUSIONS

Despite similar physician-rated severity, children with undiagnosed asthma reported significantly less frequent respiratory symptoms and health care use than children with previously diagnosed asthma. These findings suggest that the potential health gains from case detection may be smaller than expected.

Perception of breathlessness by a 3-minute respiratory exerciser test predicts asthma exacerbations: a prospective cohort study

We prospectively evaluated the use of a simple 3-Minute Respiratory Exerciser Test (3MRET) that estimates perception of dyspnea to identify patients at risk of asthma exacerbations. A total of 146 stable asthmatics (42 under-perceivers, 69 normal perceivers, and 35 over-perceivers) received follow-up for 12 months. The mean (SD) unscheduled visits to doctors among under-, normal, and over-perceivers were 1.8 (1.2), 2.2 (1.8), and 3.1 (2.3), respectively (p = 0.008). The mean (SD) hospital admissions among the groups were 1.3 (0.5), 1.2 (0.6), and 1.7 (1.3), respectively (p = 0.026). Compared to normal perceivers, over-perceivers had increased risks of unscheduled visits (OD: 5.12; 95% CI = 1.59 to 16.47) and hospital admissions (OD: 0.31; 95% CI = 0.23 to 0.41), defined as > or =2 events in 12 months. The association between over-perceiver and unscheduled visits remained significant after adjusting for forced expiratory volume in 1 second (FEV(1)). Sensitivity and specificity of over-perceivers are 77% and 47%, respectively, for unscheduled visits and 37% and 78%, respectively, for hospital admissions, with significantly better area under ROC for unscheduled visits (0.67 [95% CI = 0.56 to 0.77]; p = 0.003) than for hospital admissions (0.58 [0.471 to 0.70]; p = 0.127). We conclude that the 3MRET may have a role in identifying asthmatic patients with over-perception of dyspnea at risk of clinically important asthma exacerbations.

Perception of airflow obstruction in patients hospitalized for acute asthma

BACKGROUND

Little is known about the perception of airflow obstruction in patients hospitalized for acute asthma.

OBJECTIVES

To evaluate patient perception of airflow obstruction at hospital discharge and at a 2-week follow-up visit and to determine whether symptom control and/or severity of airflow obstruction identified patients at risk for acute asthma after discharge.

METHODS

In a prospective cohort study of inner-city adults hospitalized for acute asthma from April 1, 2001, through October 31, 2002, symptom control (Asthma Control Questionnaire) and airflow obstruction (forced expiratory volume in 1 second [FEV1] percentage predicted) were evaluated at discharge and 2 weeks after discharge. We evaluated perception of airflow obstruction (symptom control vs FEV1 percentage predicted) and perception of change in airflow obstruction (change in symptom control vs percentage change in FEV1) between the 2 visits. Acute asthma after discharge was defined as an emergency department visit or hospitalization for asthma within 90 days of discharge.

RESULTS

In fifty-one participants, symptom control was not significantly associated with airflow obstruction at hospital discharge (P = .30), indicating poor perception of airflow obstruction. Among the 41 participants (80.4% of those enrolled) who completed the follow-up visit, change in symptom control was not significantly associated with change in airflow obstruction (P = .20), indicating poor perception of change in airflow obstruction. Greater airflow obstruction at follow-up (P = .02) and a smaller improvement in airflow obstruction (P = .03), but not symptom control, were associated with a higher risk of acute asthma after discharge.

CONCLUSIONS

Patients hospitalized for acute asthma have poor perception of airflow obstruction and change in airflow obstruction. Objective measurements of lung function should guide treatment decisions after discharge in this population.

Distractive Auditory Stimuli Reduce the Unpleasantness of Dyspnea During Exercise in Patients With COPD

BACKGROUND

Dyspnea is the primary symptom limiting exercise in patients with COPD. Recent research has demonstrated that psychological factors can substantially influence the perception of dyspnea, but little is known about the modulation of perceived intensity or unpleasantness of dyspnea by attentional distraction. Therefore, we examined the impact of distractive auditory stimuli on the perception of exercise-induced dyspnea and the affective state in patients with COPD during 6-min walking tests (6MWTs).

METHODS

Twenty patients with mild-to-severe COPD (mean FEV1, 55.9% predicted) underwent two 6MWTs. Under one exercise condition, distractive auditory stimuli were presented with headphones, while the other condition was performed without auditory distraction. Lung function (FEV1), heart rate (HR), pulse oximetric saturation (SpO2), perceived intensity of dyspnea (ie, visual analog scale for perceived intensity of dyspnea [VAS-I]), and perceived unpleasantness of dyspnea (visual analog scale for perceived unpleasantness of dyspnea [VAS-U]) were measured before and after exercise. In addition, the global level of dyspnea (Borg score), positive affectivity (PA), and negative affectivity were assessed after both conditions.

RESULTS

A similar exercise level during both conditions was confirmed by comparable results in FEV1, HR, SpO2, and distances walked. During auditory distraction, Borg scores and increases in VAS-U were smaller, while PA was higher compared to the nondistraction condition (p<0.05). VAS-I did not show differences across conditions.

CONCLUSIONS

Distractive auditory stimuli decrease the global level of exercise-induced dyspnea in patients with COPD by reducing the perceived unpleasantness of dyspnea and lead to an additional increase in PA. Auditory distraction might therefore serve as an intervention for the reduction of dyspnea during exercise in this patient group.

Cardiopulmonary responses of asthmatic children to exercise: analysis of systolic and diastolic cardiac function

The aim of this study was to evaluate aerobic exercise capacity, cardiac features and function in a group of asthmatic children who underwent medical treatment. Dynamic exercise testing was done to evaluate aerobic exercise capacity. Echocardiography was performed to identify the effects that asthma-induced pulmonary changes have on respiratory and cardiac function in these patients. The study involved 20 asthmatic children (aged 7-16 years) who were followed at our hospital and 20 age- and sex-matched, healthy control subjects. Sixteen of the asthma cases were moderate and four were severe. All 40 subjects underwent similar series of assessments: multiple modes of echocardiography, treadmill stress testing, pulmonary function testing. The means for forced expiratory volume in 1 sec, forced expiratory flow 25-75%, maximal voluntary ventilation and inspiratory capacity were all significantly higher in the control group. The patient group had significantly lower mean maximal oxygen uptake and mean endurance time than the controls but there were no significant differences between the groups with respect to respiratory exchange ratio or the ventilatory threshold. The control group means for ejection fraction, fractional shortening, left ventricular mass, and left ventricular mass index were significantly higher than the corresponding patient group results. Children with moderate or severe asthma have lower aerobic capacity than healthy children of the same age. The data suggest that most of these children have normal diastolic cardiac function, but exhibit impaired systolic function and have lower LVM than healthy peers of the same age.

Cell type-specific effect of hypoxia and platelet-derived growth factor-BB on extracellular matrix turnover and its consequences for lung remodeling

Hypoxia is associated with extracellular matrix remodeling in several inflammatory lung diseases, such as fibrosis, chronic obstructive pulmonary disease, and asthma. In a human cell culture model, we assessed whether extracellular matrix modification by hypoxia and platelet-derived growth factor (PDGF) involves the action of matrix metalloproteinases (MMPs) and thereby affects cell proliferation. Expression of MMP and its activity were assessed by zymography and enzyme-linked immunosorbent assay in human lung fibroblasts and pulmonary vascular smooth muscle cells (VSMCs), and synthesis of soluble collagen type I was assessed by enzyme-linked immunosorbent assay. In both cell types, hypoxia up-regulated the expression of MMP-1, -2, and -9 precursors without subsequent activation. MMP-13 was increased by hypoxia only in fibroblasts. PDGF-BB inhibited the synthesis and secretion of all hypoxia-dependent MMP via Erk1/2 mitogen-activated protein (MAP) kinase activation. Hypoxia and PDGF-BB induced synthesis of soluble collagen type I via Erk1/2 and p38 MAP kinase. Hypoxia-induced cell proliferation was blocked by antibodies to PDGF-BB or by inhibition of Erk1/2 but not by the inhibition of MMP or p38 MAP kinase in fibroblasts. In VSMCs, hypoxia-induced proliferation involved Erk1/2 and p38 MAP kinases and was further increased by fibroblast-conditioned medium or soluble collagen type I via Erk1/2. In conclusion, hypoxia controls tissue remodeling and proliferation in a cell type-specific manner. Furthermore, fibroblasts may affect proliferation of VSMC indirectly by inducing the synthesis of soluble collagen type I.