A Concise Review of Exhaled Breath Testing for Respiratory Clinicians and Researchers

Exhaled breath contains an extensive reservoir of biomolecules. The collection of exhaled breath is noninvasive and low risk. Therefore, its testing is an appealing strategy for the discovery of biomarkers of respiratory diseases. In this concise review, we summarize the evidence of exhaled breath tests for airways diseases and respiratory infections. An overview of breath collection methods in both individuals who are spontaneously breathing and those receiving mechanical ventilation is outlined. We also highlight the challenges in exhaled breath testing and areas for future research.

Antigen stasis and airway nitrosative stress in human primary ciliary dyskinesia

Nasal nitric oxide (nNO) is low in most patients with primary ciliary dyskinesia (PCD). Decreased ciliary motion could lead to antigen stasis, increasing oxidant production and NO oxidation in the airways. This could both decrease gas phase NO and increase nitrosative stress. We studied primary airway epithelial cells from healthy controls (HCs) and patients with PCD with several different genotypes. We measured antigen clearance in fenestrated membranes exposed apically to the fluorescently labeled antigen Dermatophagoides pteronyssinus (Derp1-f). We immunoblotted for 3-nitrotyrosine (3-NT) and for oxidative response enzymes. We measured headspace NO above primary airway cells without and with a PCD-causing genotype. We measured nNO and exhaled breath condensate (EBC) H2O2 in vivo. Apical Derp1-f was cleared from HC better than from PCD cells. DUOX1 expression was lower in HC than in PCD cells at baseline and after 24-h Derp1-f exposure. HC cells had less 3-NT and NO3- than PCD cells. However, NO consumption by HC cells was less than that by PCD cells; NO loss was prevented by superoxide dismutase (SOD) and by apocynin. nNO was higher in HCs than in patients with PCD. EBC H2O2 was lower in HC than in patients with PCD. The PCD airway epithelium does not optimally clear antigens and is subject to oxidative and nitrosative stress. Oxidation associated with antigen stasis could represent a therapeutic target in PCD, one with convenient monitoring biomarkers.NEW & NOTEWORTHY The PCD airway epithelium does not optimally clear antigens, and antigen exposure can lead to NO oxidation and nitrosative stress. Oxidation caused by antigen stasis could represent a therapeutic target in PCD, and there are convenient monitoring biomarkers.

Desalkylgidazepam blood concentrations in 63 forensic investigation cases

Desalkylgidazepam, also known as bromonordiazepam, is the latest designer benzodiazepine to appear in postmortem blood samples in British Columbia. Our laboratory was first alerted to the presence of desalkylgidazepam in seized drug samples in May 2022, and the analyte was added to an in-house library shortly thereafter. Previously acquired spectra from routine death investigation cases were reprocessed using the updated library with the first presumptive identification of desalkylgidazepam occurring in a sample received in April 2022. A standard addition method for the quantitation of desalkylgidazepam in blood samples (from femoral, iliac, jugular and subclavian veins) was validated and consequently used to confirm presence and concentrations of the drug in 63 cases, with an average concentration of 42.2 ± 44.0 ng/mL (median concentration: 24.5 ng/mL; range: 3.7-220.6 ng/mL). Similar to detections of other novel benzodiazepines, co-occurrence of desalkylgidazepam with opioids and/or stimulants was common. To our knowledge, this paper is the first to report desalkylgidazepam concentrations in postmortem blood samples.

Nocturnal High-Flow Nasal Cannula Therapy and Sinonasal Symptoms During Cystic Fibrosis Exacerbations

BACKGROUND

Both nasal obstruction and sleep disturbance are common in patients with cystic fibrosis (CF). In patients with obstructive sleep apnea (OSA), studies suggest that these conditions are related and that nasal congestion improves with CPAP therapy. We hypothesized that subjects admitted to hospital for therapy of an exacerbation of CF would have both nasal symptoms and sleep disturbance and that these would improve with the initiation of nocturnal high-flow nasal cannula therapy (HFNC).

METHODS

Twenty-five subjects with an exacerbation of CF were enrolled to randomly receive either 5 d of nocturnal HFNC at 20 L/min in the treatment group or 5 L/min of nocturnal nasal cannula air at ambient temperature and humidity in the low-flow group. On the first and last day of the study, the Sino-Nasal Outcome Test (SNOT-20) was administered to evaluate nasal symptoms, and sleep quality was measured using the Actiwatch 2.

RESULTS

Fifteen subjects completed the study (6 HFNC, 9 low flow). We confirmed that subjects had significant sleep disturbance that did not improve over the 5 d of the study. Subjects also had disturbing nasal symptoms that significantly improved only in those receiving HFNC (pre 14 [20] vs post 6 [13], P = .027).

CONCLUSIONS

Similar to what has been reported in older subjects with OSA, nocturnal HFNC improves sinonasal symptoms in subjects with an exacerbation of CF. There was no measurable effect on sleep quality, which may be due to the short duration of the study, or to subjects being evaluated while being treated in a hospital setting.

Defining and Promoting Pediatric Pulmonary Health: Developing Biomarkers for Pulmonary Health

Children with inherited and/or acquired respiratory disorders often arrive in adolescence and adulthood with diminished lung function that might have been detected and prevented had better mechanisms been available to identify and to assess progression of disease. Fortunately, advances in genetic assessments, low-cost diagnostics, and minimally- invasive novel biomarkers are being developed to detect and to treat respiratory diseases before they give rise to loss of life or lung function. This paper summarizes the Developing Biomarkers for Pulmonary Health sessions of the National Heart, Lung, and Blood Institute- sponsored 2021 Defining and Promoting Pediatric Pulmonary Health workshop. These sessions discussed genetic testing, pulse oximetry, exhaled nitric oxide, and novel biomarkers related to childhood lung diseases.

Effects of pH alteration on respiratory syncytial virus in human airway epithelial cells

Background

Respiratory syncytial virus (RSV) is a leading cause of respiratory distress and hospitalisation in the paediatric population. Low airway surface pH impairs antimicrobial host defence and worsens airway inflammation. Inhaled Optate safely raises airway surface pH in humans and raises intracellular pH in primary human airway epithelial cells (HAECs) in vitro. We aimed to determine whether raising intracellular pH with Optate would decrease infection and replication of RSV in primary HAECs.

Methods

We cultured HAECs from healthy subjects in both air-liquid interface and submerged conditions. We infected HAECs with green fluorescent protein-labelled RSV (GFP-RSV; multiplicity of infection=1) and treated them with Optate or PBS control. We collected supernatant after a 4-h incubation and then every 24 h. We used fluorescence intensity, fluorescent particle counts, plaque assays, Western blots and ELISA to quantitate infection.

Results

In submerged culture, fluorescence intensity decreased in Optate-treated cells (48 h p=0.0174, 72 h p≤0.001). Similarly, Optate treatment resulted in decreased fluorescent particle count (48 h p=0.0178, 72 h p=0.0019) and plaque-forming units (48 h p=0.0011, 72 h p=0.0148) from cell culture supernatant. In differentiated HAECs cultured at ALI, Optate treatment decreased fluorescence intensity (p≤0.01), GFP via Western blot and ELISA (p<0.0001), and RSV-fusion protein via ELISA (p=0.001). Additionally, RSV infection decreased as Optate concentration increased in a dose-dependent manner (p<0.001).

Conclusions

Optate inhibits RSV infection in primary HAECs in a dose-dependent manner. These findings suggest that Optate may have potential as an inhaled therapeutic for patients with RSV.

Methods to Detect Volatile Organic Compounds for Breath Biopsy Using Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry

Volatile organic compounds (VOCs) are byproducts from metabolic pathways that can be detected in exhaled breath and have been reported as biomarkers for different diseases. The gold standard for analysis is gas chromatography-mass spectrometry (GC-MS), which can be coupled with various sampling methods. The current study aims to develop and compare different methods for sampling and preconcentrating VOCs using solid-phase microextraction (SPME). An in-house sampling method, direct-breath SPME (DB-SPME), was developed to directly extract VOCs from breath using a SPME fiber. The method was optimized by exploring different SPME types, the overall exhalation volume, and breath fractionation. DB-SPME was quantitatively compared to two alternative methods involving the collection of breath in a Tedlar bag. In one method, VOCs were directly extracted from the Tedlar bag (Tedlar-SPME) and in the other, the VOCs were cryothermally transferred from the Tedlar bag to a headspace vial (cryotransfer). The methods were verified and quantitatively compared using breath samples (n = 15 for each method respectively) analyzed by GC-MS quadrupole time-of-flight (QTOF) for compounds including but not limited to acetone, isoprene, toluene, limonene, and pinene. The cryotransfer method was the most sensitive, demonstrating the strongest signal for the majority of the VOCs detected in the exhaled breath samples. However, VOCs with low molecular weights, including acetone and isoprene, were detected with the highest sensitivity using the Tedlar-SPME. On the other hand, the DB-SPME was less sensitive, although it was rapid and had the lowest background GC-MS signal. Overall, the three breath-sampling methods can detect a wide variety of VOCs in breath. The cryotransfer method may be optimal when collecting a large number of samples using Tedlar bags, as it allows the long-term storage of VOCs at low temperatures (-80 °C), while Tedlar-SPME may be more effective when targeting relatively small VOCs. The DB-SPME method may be the most efficient when more immediate analyses and results are required.

In vitro-in vivo correlation of aerosol deposition before and after metered-dose inhaler coaching in healthy children

Although pressurized metered dose inhaler (pMDI) education is a routine part of childhood asthma management and encouraging "optimal breathing patterns" (i.e., slowly, deeply, completely, and with a mouth seal on the mouthpiece) is an integral part of recommended pMDI education, there is currently no quantifiable way to determine if a child is inhaling their medication correctly or optimally through a valved holding chamber (VHC). The TipsHaler™ (tVHC) is a prototype VHC device that measures inspiratory time, flow, and volume without changing the properties of the medication aerosol. The measurements in vivo recorded by the tVHC can be downloaded and transferred to a spontaneous breathing lung model to simulate the inhalational patterns in vitro and also determine the deposition of inhaled aerosol mass with each pattern. We hypothesized that pediatric patients' inhalational patterns when using a pMDI would improve after active coaching via tVHC. This would increase the pulmonary deposition of inhaled aerosols in an in vitro model. To test this hypothesis, we conducted a single-site, prospective, pilot, pre-and-post intervention study paired with a bedside-to-bench experiment. Healthy, inhaler-naïve subjects used a placebo inhaler in conjunction with the tVHC before and after coaching and recorded inspiratory parameters. These recordings were then implemented into a spontaneous breathing lung model during albuterol MDI delivery, and pulmonary deposition of albuterol was quantified. In this pilot study, active coaching resulted in a statistically significant increase in inspiratory time (n = 8, p = 0.0344, 95%CI: 0.082 to ∞). tVHC recorded inspiratory parameters obtained from patients were successfully implemented in the in vitro model, which demonstrated that both inspiratory time (n = 8, r = 0.78, p < 0.001, 95%CI: 0.47 to 0.92) and volume (n = 8, r = 0.58, p = 0.0186, 95%CI: 0.15 to 0.85) strongly correlate with pulmonary deposition of inhaled drugs.

Volatile metabolites differentiate air-liquid interface cultures after infection with Staphylococcus aureus

Early detection of lung infection is critical to clinical diagnosis, treatment, and monitoring. Measuring volatile organic compounds (VOCs) in exhaled breath has shown promise as a rapid and accurate method of evaluating disease metabolism and phenotype. However, further investigations of the role and function of VOCs in bacterial-host-stress response is required and this can only be realised through representative in vitro models. In this study we sampled VOCs from the headspace of A549 cells at an air-liquid interface (ALI). We hypothesised VOC sampling from ALI cultures could be used to profile potential biomarkers of S. aureus lung infection. VOCs were collected using thin film microextraction (TFME) and were analysed by thermal desorption-gas chromatography-mass spectrometry. After optimising ALI cultures, we observed seven VOCs changed between A549 and media control samples. After infecting cells with S. aureus, supervised principal component-discriminant function analysis revealed 22 VOCs were found to be significantly changed in infected cells compared to uninfected cells (p < 0.05), five of which were also found in parallel axenic S. aureus cultures. We have demonstrated VOCs that could be used to identify S. aureus in ALI cultures, supporting further investigation of VOC analysis as a highly sensitive and specific test for S. aureus lung infection.

Bromazolam Blood Concentrations in Post-mortem Cases - A British Columbia Perspective

Bromazolam is a designer benzodiazepine that was first detected in British Columbia in January 2021. Post-mortem cases were analysed using a comprehensive blood drug screen by liquid-chromatography high resolution mass spectrometry before being retrospectively analysed with an in-house Novel Psychoactive Substances (NPS) data processing method. Bromazolam was detected in 41 post-mortem cases in 2021 and quantitatively confirmed by standard addition, using liquid chromatography tandem mass spectrometry. The mean bromazolam concentration observed was 11.4 ± 53.7 ng/mL (median concentration: 1.6 ng/mL), with a range from 0.5 to 319.3 ng/mL, and the majority of cases co-occurring with fentanyl. These low concentrations may be indicative of a presumed enhancement of opioid effects rather than being used as a standalone drug. Bromazolam was always detected with opioids (fentanyl, carfentanil), stimulants (methamphetamine) and/or other benzodiazepines (etizolam, flualprazolam). To our knowledge, this is the first report to provide concentrations of bromazolam in post-mortem blood samples in Canada.

Preliminary method for profiling volatile organic compounds in breath that correlate with pulmonary function and other clinical traits of subjects diagnosed with cystic fibrosis: a pilot study

Cystic fibrosis (CF) is characterized by chronic respiratory infections which progressively decrease lung function over time. Affected individuals experience episodes of intensified respiratory symptoms called pulmonary exacerbations (PEx) which accelerate pulmonary function decline and decrease survival. There is no standard classification for PEx, which results in treatments that are heterogeneous. Improving PEx classification and management is a significant priority for people with CF. Previous studies have shown volatile organic compounds (VOCs) in exhaled breath can be used as biomarkers because they are products of metabolic pathways dysregulated by different diseases. To provide insights on PEx classification and other clinical factors, exhaled breath was collected from subjects with CF, with some experiencing PEx and others at baseline. Exhaled breath was collected in Tedlar bags during tidal breathing for VOC analysis by solid phase microextraction coupled to gas chromatography-mass spectrometry. Statistical significance testing between quantitative and categorical clinical variables displayed percent-predicted forced expiratory volume in one second (FEV1pp) was decreased in subjects experiencing PEx. VOCs correlating with other clinical variables (body mass index, age, use of highly effective modulator therapies, and need for antibiotics) were also explored. VOCs correlating to potential confounding variables were removed and analyzed by regression for correlations with FEV1pp measurements. The VOC with the highest correlation with FEV1pp (3,7-dimethyldecane) also gave the lowest p-value when comparing subjects at baseline and during PEx. Receiver operator characteristic curves showed 3,7-dimethyldecane had a higher ability to classify PEx (area under the curve (AUC) = 0.91) relative to FEV1pp values at collection (AUC = 0.83). However, normalized ΔFEV1pp values had the highest capability to distinguish PEx (AUC = 0.93). These results show that exhaled VOCs may be a source of biomarkers for various clinical traits of CF, including PEx, that should be explored in larger sample cohorts and validation studies.

The physics of human breathing: flow, timing, volume, and pressure parameters for normal, on-demand, and ventilator respiration

Normal breathing for healthy humans is taken for granted; it occurs without conscious effort using ambient (1-atmosphere) pressure with 21% oxygen (O2) concentration. The body automatically adjusts for stress, exercise, altitude, and mild disease by increasing the volume and frequency of breathing. Longer term adaptations for exercise and altitude include increases in red blood cell counts and higher concentrations of capillaries in muscle tissue. When more challenging external environmental conditions or pulmonary illnesses exceed the capability for these adaptations, the human system requires technology to maintain sufficient ventilation to preserve life. On the environmental side there are two conditions to be addressed: toxicity of the surrounding atmosphere and changes in external pressure and O2concentration. On the medical side, mechanisms for assisting breathing include O2supplementation at ambient pressure, positive pressure/flow without additional O2, or a combination of both. This overview describes the various technologies applied to maintaining a safe breathing environment. Topics for environmental intervention include filter-based and flowing air-supply masks for toxic environments (occupational and laboratory protection), and on-demand gas supply systems for firefighters, self-contained underwater breathing apparatus divers, and altitude (high performance aircraft, spacecraft) applications. The topics for medical intervention include nasal cannula, continuous positive airway pressure, and medical ventilators. The primary purpose of this article is to provide a basic understanding of normal human breathing and the adaptation of breathing in different environments using available technologies.

Benefits of Airway Androgen Receptor Expression in Human Asthma

Rationale: Androgens are potentially beneficial in asthma, but AR (androgen receptor) has not been studied in human airways.Objectives: To measure whether AR and its ligands are associated with human asthma outcomes.Methods: We compared the effects of AR expression on lung function, symptom scores, and fractional exhaled nitric oxide (Fe_NO) in adults enrolled in SARP (Severe Asthma Research Program). The impact of sex and of androgens on asthma outcomes was also evaluated in the SARP with validation studies in the Cleveland Clinic Health System and the NHANES (U.S. National Health and Nutrition Examination Survey).Measurements and Main Results: In SARP (n = 128), AR gene expression from bronchoscopic epithelial brushings was positively associated with both FEV₁/FVC ratio (R² = 0.135, P = 0.0002) and the total Asthma Quality of Life Questionnaire score (R² = 0.056, P = 0.016) and was negatively associated with Fe_NO (R² = 0.178, P = 9.8 × 10^-6) and NOS2 (nitric oxide synthase gene) expression (R² = 0.281, P = 1.2 × 10^-10). In SARP (n = 1,659), the Cleveland Clinic Health System (n = 32,527), and the NHANES (n = 2,629), women had more asthma exacerbations and emergency department visits than men. The levels of the AR ligand precursor dehydroepiandrosterone sulfate correlated positively with the FEV₁ in both women and men.Conclusions: Higher bronchial AR expression and higher androgen levels are associated with better lung function, fewer symptoms, and a lower Fe_NO in human asthma. The role of androgens should be considered in asthma management.

Somatic cell hemoglobin modulates nitrogen oxide metabolism in the human airway epithelium

Endothelial hemoglobin (Hb)α regulates endothelial nitric oxide synthase (eNOS) biochemistry. We hypothesized that Hb could also be expressed and biochemically active in the ciliated human airway epithelium. Primary human airway epithelial cells, cultured at air–liquid interface (ALI), were obtained by clinical airway brushings or from explanted lungs. Human airway Hb mRNA data were from publically available databases; or from RT-PCR. Hb proteins were identified by immunoprecipitation, immunoblot, immunohistochemistry, immunofluorescence and liquid chromatography- mass spectrometry. Viral vectors were used to alter Hbβ expression. Heme and nitrogen oxides were measured colorimetrically. Hb mRNA was expressed in human ciliated epithelial cells. Heme proteins (Hbα, β, and δ) were detected in ALI cultures by several methods. Higher levels of airway epithelial Hbβ gene expression were associated with lower FEV₁ in asthma. Both Hbβ knockdown and overexpression affected cell morphology. Hbβ and eNOS were apically colocalized. Binding heme with CO decreased extracellular accumulation of nitrogen oxides. Human airway epithelial cells express Hb. Higher levels of Hbβ gene expression were associated with airflow obstruction. Hbβ and eNOS were colocalized in ciliated cells, and heme affected oxidation of the NOS product. Epithelial Hb expression may be relevant to human airways diseases.

2020 Year in Review: Pharmacologic Treatments for COVID-19

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 infection, has led to a pandemic of acute respiratory illness. Pharmacologic treatments for COVID-19 have included treatments that target infection prevention, prevention of viral replication, reduce inflammation, and manage symptoms of respiratory failure caused by the disease. This is a review of key pharmacologic treatments for COVID-19 based on peer-reviewed articles from 2020.

The remaining barriers to normalcy in CF: Advances in assessment of CF lung disease

Despite early diagnosis of cystic fibrosis (CF) through newborn screening, a substantial proportion of infants and young children with CF still demonstrate physiologic and structural evidence of lung disease progression, such as obstructive airway disease and bronchiectasis. The growing availability of highly effective CF transmembrane conductance regulatory modulator therapy to the vast majority of people with CF has led to the potential to alter the natural history of CF lung disease, but to assess the full impact of these therapies on CF lung disease and to help guide treatment, sensitive measures of early and mild disease are needed. Chest imaging using computed tomography or magnetic resonance imaging is one approach, but technologic barriers and/or concern about exposure to ionizing radiation may limit its use. However, advances in physiologic measurement techniques and exhaled breath analysis offer another option for assessment of CF lung disease.

A Treatment to Eliminate SARS-CoV-2 Replication in Human Airway Epithelial Cells Is Safe for Inhalation as an Aerosol in Healthy Human Subjects

BACKGROUND

Low airway surface pH is associated with many airway diseases, impairs antimicrobial host defense, and worsens airway inflammation. Inhaled Optate is designed to safely raise airway surface pH and is well tolerated in humans. Raising intracellular pH partially prevents activation of SARS-CoV-2 in primary normal human airway epithelial (NHAE) cells, decreasing viral replication by several mechanisms.

METHODS

We grew primary NHAE cells from healthy subjects, infected them with SARS-CoV-2 (isolate USA-WA1/2020), and used clinical Optate at concentrations used in humans in vivo to determine whether Optate would prevent viral infection and replication. Cells were pretreated with Optate or placebo prior to infection (multiplicity of infection = 1), and viral replication was determined with plaque assay and nucleocapsid (N) protein levels. Healthy human subjects also inhaled Optate as part of a Phase 2a safety trial.

RESULTS

Optate almost completely prevented viral replication at each time point between 24 h and 120 h, relative to placebo, on both plaque assay and N protein expression (P < .001). Mechanistically, Optate inhibited expression of major endosomal trafficking genes and raised NHAE intracellular pH. Optate had no effect on NHAE cell viability at any time point. Inhaled Optate was well tolerated in 10 normal subjects, with no change in lung function, vital signs, or oxygenation.

CONCLUSIONS

Inhaled Optate may be well suited for a clinical trial in patients with pulmonary SARS-CoV-2 infection. However, it is vitally important for patient safety that formulations designed for inhalation with regard to pH, isotonicity, and osmolality be used. An inhalational treatment that safely prevents SARS-CoV-2 viral replication could be helpful for treating patients with pulmonary SARS-CoV-2 infection.

Blood Biomarkers for Detection of Brain Injury in COVID-19 Patients

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus attacks multiple organs of coronavirus disease 2019 (COVID-19) patients, including the brain. There are worldwide descriptions of neurological deficits in COVID-19 patients. Central nervous system (CNS) symptoms can be present early in the course of the disease. As many as 55% of hospitalized COVID-19 patients have been reported to have neurological disturbances three months after infection by SARS-CoV-2. The mutability of the SARS-COV-2 virus and its potential to directly affect the CNS highlight the urgency of developing technology to diagnose, manage, and treat brain injury in COVID-19 patients. The pathobiology of CNS infection by SARS-CoV-2 and the associated neurological sequelae of this infection remain poorly understood. In this review, we outline the rationale for the use of blood biomarkers (BBs) for diagnosis of brain injury in COVID-19 patients, the research needed to incorporate their use into clinical practice, and the improvements in patient management and outcomes that can result. BBs of brain injury could potentially provide tools for detection of brain injury in COVID-19 patients. Elevations of BBs have been reported in cerebrospinal fluid (CSF) and blood of COVID-19 patients. BB proteins have been analyzed in CSF to detect CNS involvement in patients with infectious diseases, including human immunodeficiency virus and tuberculous meningitis. BBs are approved by the U.S. Food and Drug Administration for diagnosis of mild versus moderate traumatic brain injury and have identified brain injury after stroke, cardiac arrest, hypoxia, and epilepsy. BBs, integrated with other diagnostic tools, could enhance understanding of viral mechanisms of brain injury, predict severity of neurological deficits, guide triage of patients and assignment to appropriate medical pathways, and assess efficacy of therapeutic interventions in COVID-19 patients.

Year in Review 2018: Pediatric Mechanical Ventilation

Mechanical ventilation is frequently used in pediatric patients to ensure adequate gas exchange, ameliorate respiratory distress, and enable resolution of pulmonary or other disorders. However, a number of important challenges remain in the pediatric population because there is a paucity of large-scale randomized controlled trials to generate data and inform clinical practice. This review summarizes a number of discoveries and advances that have been made in pediatric mechanical ventilation from June 2017 to December 2018.

Local Effects of Two Intravenous Formulations of Pulmonary Vasodilators on Airway Epithelium

BACKGROUND

Intravenous formulations of epoprostenol are frequently delivered via nebulizer to treat pulmonary hypertension in acutely ill patients. Although their efficacy as pulmonary vasodilators has been shown to be comparable to inhaled nitric oxide, the local effects of these formulations within the airways have not been determined. We hypothesized that the alkaline diluents of these compounds would lead to increased airway epithelial cell death and ciliary cessation.

METHODS

Human bronchial epithelial cells were exposed to epoprostenol in glycine and arginine diluents or control fluid. Ciliary beat frequency, lactate dehydrogenase, and total RNA levels were measured before and after exposure. Results were compared between exposure and control groups.

RESULTS

Ciliary beat frequency ceased immediately after exposure to epoprostenol with both diluents. Lactate dehydrogenase levels increased by 200% after exposure to epoprostenol and glycine diluent (P = .002). Total RNA levels were undetectable after exposure to epoprostenol and arginine, indicating complete cell death and lysis (P = .015). Ciliary beat frequency ceased after 30 s of exposure to epoprostenol and glycine (P = .008). There was no difference between cells exposed to epoprostenol and those exposed only to diluent.

CONCLUSIONS

Exposure to intravenous formulations of epoprostenol in glycine and arginine caused increased cell death and ciliary cessation in bronchial epithelial cells. These findings suggest that undesired local effects may occur when these compounds are delivered as inhaled aerosols to patients.

2019 Year in Review: Asthma

Asthma is an obstructive airway disease affecting children and adults throughout the world. It is a heterogeneous disease with a variety of causes and treatments. Research in the diagnosis, treatment, and management of asthma is ongoing, and there were > 8,000 publications on asthma in 2019. This paper reviews several research articles about asthma from 2019 that are most relevant for practicing respiratory therapists caring for patients with asthma.

Exhaled breath testing - A tool for the clinician and researcher

Exhaled breath is a robust matrix of biomarkers divided between three fractions - gaseous breath, volatile breath, and breath condensate. Breath is collected non-invasively through bags (for gaseous breath), cold condensation chambers (breath condensate), and adsorbent traps (volatile breath). Due to the incredibly dilute nature of breath matrices, breath biomarker analysis requires precise analytical techniques, highly sensitive technology and often challenges the limit of detection of even the most advanced assays. Interest and advances in breath collection, analysis, and use have increased in recent years largely due to advances in analytical technology. Approved and validated breath tests are available as tools for researchers and clinicians. Novel development is ongoing. This article reviews the current applications for exhaled breath biomarkers.

Tissue Factor Facilitates Wound Healing in Human Airway Epithelial Cells

BACKGROUND

Tissue factor (TF) canonically functions as the initiator of the coagulation cascade. TF levels are increased in inflamed airways and seem to be important for tumor growth and metastasis. We hypothesized that airway epithelia release TF as part of a wound repair program.

OBJECTIVES

The goal of this study was to evaluate whether airway epithelia release TF in response to pro-inflammatory stimuli and to investigate roles of TF in cell growth and repair.

METHODS

Airway epithelial cells were exposed to 10 μg/mL of lipopolysaccharide or 1 ng/mL of transforming growth factor β (TGF-β). TF and TGF-β messenger RNA and protein were measured in cell lysate and culture media, respectively. Signaling pathways were evaluated by using selective agonists and inhibitors. Airway epithelia were mechanically injured in the presence of TF and tissue factor pathway inhibitor to investigate their roles in wound repair.

RESULTS

TF protein levels increased in cell media after exposure to lipopolysaccharide (P < .01) but only in growing cells, and this action was blocked when exposed to an extracellular signal-regulated kinase inhibitor or a "small" worm phenotype and mothers against Decapentaplegic inhibitor. TF protein also increased in the presence of TGF-β (P < .05). Exposure to TF pathway inhibitor decreased the rate of cell growth by 60% (P < .05), and exposure to TF increased the rate of airway healing after injury by 19% (P < .05).

CONCLUSIONS

Growing airway epithelia release TF when exposed to lipopolysaccharide or TGF-β. TF reduces wound-healing time in airway epithelia and therefore may be important to airway recovery after injury.

Exhaled Breath Condensate: An Update

Exhaled breath condensate (EBC) is a promising source of biomarkers of lung disease. EBC research and utility has increased substantially over the past 2 decades. This review summarizes many of the factors regarding the composition of EBC, its collection, and analysis for the utility of both clinicians and researchers.

Administration of Inhaled Pulmonary Vasodilators to the Mechanically Ventilated Neonatal Patient

Pulmonary hypertension is a life-threatening condition that affects people of all ages that can occur as an idiopathic disorder at birth or as part of a variety of cardiovascular and infectious disorders. It is commonly treated with inhaled pulmonary vasodilators such as nitric oxide and less frequently using formulations and analogs of prostacyclin. To minimize systemic effects and preserve pulmonary vasodilation, vasodilators are often administered directly into the airway. Nitric oxide is the only USA Food and Drug Administration-approved inhaled pulmonary vasodilator that can be used during mechanical ventilation. Over the past two decades, interest has grown in the use of aerosolized prostacyclin and prostacyclin analogs for the treatment of pulmonary hypertension during mechanical ventilation. Clinicians who administer inhaled prostacyclin may not have a clear understanding of its risks because of the lack of data from large clinical trials examining safety and efficacy; moreover, its safe use remains poorly documented. The off-label use of drugs is legitimate, but prescribers must recognize the potential complications and liability in doing so. This manuscript aims to address potential problems related to the aerosol administration of pulmonary vasodilators in the mechanically ventilated neonatal patient.

Changes in Cerebral Blood Flow during an Alteration in Glycemic State in a Large Non-human Primate (Papio hamadryas sp.)

Changes in cerebral blood flow (CBF) during a hyperglycemic challenge were mapped, using perfusion-weighted MRI, in a group of non-human primates. Seven female baboons were fasted for 16 h prior to 1-h imaging experiment, performed under general anesthesia, that consisted of a 20-min baseline, followed by a bolus infusion of glucose (500 mg/kg). CBF maps were collected every 7 s and blood glucose and insulin levels were sampled at regular intervals. Blood glucose levels rose from 51.3 ± 10.9 to 203.9 ± 38.9 mg/dL and declined to 133.4 ± 22.0 mg/dL, at the end of the experiment. Regional CBF changes consisted of four clusters: cerebral cortex, thalamus, hypothalamus, and mesencephalon. Increases in the hypothalamic blood flow occurred concurrently with the regulatory response to systemic glucose change, whereas CBF declined for other clusters. The return to baseline of hypothalamic blood flow was observed while CBF was still increasing in other brain regions. The spatial pattern of extra-hypothalamic CBF changes was correlated with the patterns of several cerebral networks including the default mode network. These findings suggest that hypothalamic blood flow response to systemic glucose levels can potentially be explained by regulatory activity. The response of extra-hypothalamic clusters followed a different time course and its spatial pattern resembled that of the default-mode network.

Autoimmune myelofibrosis with pancytopenia as a presenting manifestation of systemic lupus erythematosus responsive to mycophenolate mofetil

Hematological abnormalities, such as anemia, leucopenia, and thrombocytopenia, secondary to peripheral destruction, are common in systemic lupus erythematosus (SLE). However, cytopenias from autoimmune myelofibrosis (AIMF) are extremely uncommon in SLE, with less than 40 reported cases in the literature. We report the case of a 33-year-old female who presented with bullous skin lesions and pancytopenia as the presenting manifestation of what was ultimately diagnosed as SLE with AIMF. She responded well to glucocorticoids and mycophenolate mofetil.

The effects of lung recruitment maneuvers on exhaled breath condensate pH

Exhaled breath condensate (EBC) pH serves as a surrogate marker of airway lining fluid (ALF) pH and can be used to evaluate airway acidification (AA). AA is known to be present in acute respiratory distress syndrome (ARDS) and can be evaluated via continuous EBC pH measurement during mechanical ventilation. Lung recruitment maneuvers (LRMs) are utilized in the treatment of ARDS, however, their impact on EBC pH has never been explored. Here we described the acute effects of two commonly used LRMs on EBC pH. In a prospective, non-randomized, serial exposure study, 10 intubated pediatric subjects with acute respiratory distress syndrome sequentially underwent: a period of baseline ventilation, sustained inflation (SI) maneuver of 40 cm H2O for 40 s, open lung ventilation, staircase recruitment strategy (SRS) (which involves a systematic ramping of plateau pressures in 5 cm H2O increments, starting at 30 cm H2O), and PEEP titration. Maximum lung recruitment during the SRS is defined as a PaO2 + PaCO2 of  >400 mmHg. Following lung recruitment, PEEP titration was conducted from 20 cm H2O in 2 cm H2O decrements until a PaO2 + PaCO2 was  <380 and then increased by 2 cm H2O. EBC pH, arterial blood gases, lung mechanics, hemodynamics, and function residual capacity were obtained following each phase of the LRM and observational period. Seven out of 10 patients were able to reach maximum lung recruitment. Baseline EBC pH (6.38   ±   0.37) did not correlate with disease severity defined by PaO2/FiO2 ratio or oxygenation index (OI). Average EBC pH differed between phases and decreased after LRM (p = 0.001). EBC pH is affected by LRMs. EBC acidification following LRMs may represent a washout effect of opening acidic lung units and ventilating them or acute AA resulting from LRM.

Safety of an alkalinizing buffer designed for inhaled medications in humans

BACKGROUND

Airway acidification plays a role in disorders of the pulmonary tract. We hypothesized that the inhalation of alkalinized glycine buffer would measurably alkalinize the airways without compromising lung function or causing adverse events. We evaluated the safety of an inhaled alkaline glycine buffer in both healthy subjects and in subjects with stable obstructive airway disease.

METHODS

This work includes 2 open-label safety studies. The healthy controls were part of a phase 1 safety study of multiple inhalations of low-dose alkaline glycine buffer; nebulized saline was used as a comparator in 8 of the healthy controls. Subsequently, a phase 2 study in subjects with stable obstructive airway disease was completed using a single nebulized higher-dose strategy of the alkaline inhalation. We studied 20 non-smoking adults (10 healthy controls and 10 subjects with obstructive airway disease), both at baseline and after inhalation of alkaline buffer. We used spirometry and vital signs as markers of clinical safety. We used changes in fraction of exhaled nitric oxide (NO) and exhaled breath condensate (EBC) pH as surrogate markers of airway pH modification.

RESULTS

Alkaline glycine inhalation was tolerated by all subjects in both studies, with no adverse effects on spirometric parameters or vital signs. Airway alkalinization was confirmed by a median increase in EBC pH of 0.235 pH units (IQR 0.56-0.03, P = .03) in subjects after inhalation of the higher-dose alkaline buffer (2.5 mL of 100 mmol/L glycine).

CONCLUSIONS

Alkalinization of airway lining fluid is accomplished with inhalation of alkaline glycine buffer and causes no adverse effects on pulmonary function or vital signs.

High titers of IgE antibody to dust mite allergen and risk for wheezing among asthmatic children infected with rhinovirus

Background

The relevance of allergic sensitization, as judged by titers of serum IgE antibodies, to the risk of an asthma exacerbation caused by rhinovirus is unclear.

Objective

We sought to examine the prevalence of rhinovirus infections in relation to the atopic status of children treated for wheezing in Costa Rica, a country with an increased asthma burden.

Methods

The children enrolled (n = 287) were 7 through 12 years old. They included 96 with acute wheezing, 65 with stable asthma, and 126 nonasthmatic control subjects. PCR methods, including gene sequencing to identify rhinovirus strains, were used to identify viral pathogens in nasal washes. Results were examined in relation to wheezing, IgE, allergen-specific IgE antibody, and fraction of exhaled nitric oxide levels.

Results

Sixty-four percent of wheezing children compared with 13% of children with stable asthma and 13% of nonasthmatic control subjects had positive test results for rhinovirus (P < .001 for both comparisons). Among wheezing subjects, 75% of the rhinoviruses detected were group C strains. High titers of IgE antibodies to dust mite allergen (especially Dermatophagoides species) were common and correlated significantly with total IgE and fraction of exhaled nitric oxide levels. The greatest risk for wheezing was observed among children with titers of IgE antibodies to dust mite of 17.5 IU/mL or greater who tested positive for rhinovirus (odds ratio for wheezing, 31.5; 95% CI, 8.3-108; P < .001).

Conclusions

High titers of IgE antibody to dust mite allergen were common and significantly increased the risk for acute wheezing provoked by rhinovirus among asthmatic children.

Craniorachischisis and omphalocele in a stillborn cynomolgus monkey (Macaca fascicularis)

Nonhuman primates have been a common animal model to evaluate experimentally induced malformations. Reports on spontaneous malformations are important in determining the background incidence of congenital anomalies in specific species and in evaluating experimental results. Here we report on a stillborn cynomolgus monkey (Macaca fascicularis) with multiple congenital anomalies from the colony maintained at the Southwest National Primate Research Center at the Texas Biomedical Research Institute, San Antonio, Texas. Physical findings included low birth weight, craniorachischisis, facial abnormalities, omphalocele, malrotation of the gut with areas of atresia and intussusception, a Meckel diverticulum, arthrogryposis, patent ductus arteriosus, and patent foramen ovale. The macaque had normal male external genitalia, but undescended testes. Gestational age was unknown but was estimated from measurements of the limbs and other developmental criteria. Although cytogenetic analysis was not possible due to the tissues being in an advanced state of decomposition, array Comparative Genomic Hybridization analysis using human bacterial artificial chromosome clones was successful in effectively eliminating aneuploidy or any copy number changes greater than approximately 3-5 Mb as a cause of the malformations. Further evaluation of the animal included extensive imaging of the skeletal and neural tissue defects. The animal's congenital anomalies are discussed in relation to the current hypotheses attempting to explain the frequent association of neural tube defects with other abnormalities.

A Postnatal Pax7 Progenitor Gives Rise to Pituitary Adenomas

Pituitary adenomas are classified into functioning and nonfunctioning (silent) tumors on the basis of hormone secretion. However, the mechanism of tumorigenesis and the cell of origin for pituitary adenoma subtypes remain to be elucidated. Employing a tamoxifen-inducible mouse model, we demonstrate that a novel postnatal Pax7(+) progenitor cell population in the pituitary gland gives rise to silent corticotroph macro-adenomas when the retinoblastoma tumor suppressor is conditionally deleted. While Pax transcriptional factors are critical for embryonic patterning as well as postnatal stem cell renewal for many organs, we have discovered that Pax7 marks a restricted cell population in the postnatal pituitary intermediate lobe. This Pax7(+) early progenitor cell population is overlapping but ontologically downstream of the Nestin(+) pituitary stem cell population, yet upstream of another newly discovered Myf6(+) late progenitor cell population. Interestingly, the Pax7(+) progenitor cell population is evolutionarily conserved in primates and humans, and Pax7 expression is maintained not only in murine tumors but also in human functioning and silent corticotropinomas. Taken together, our results strongly suggest that human silent corticotroph adenomas may in fact arise from a Pax7 lineage of the intermediate lobe, a region of the human pituitary bearing closer scientific interest as a reservoir of pituitary progenitor cells.

Synthesis and biological evaluation of sphingosine kinase substrates as sphingosine-1-phosphate receptor prodrugs

In the search for bioactive sphingosine 1-phosphate (S1P) receptor ligands, a series of 2-amino-2-heterocyclic-propanols were synthesized. These molecules were discovered to be substrates of human-sphingosine kinases 1 and 2 (SPHK1 and SPHK2). When phosphorylated, the resultant phosphates showed varied activities at the five sphingosine-1-phosphate (S1P) receptors (S1P(1-5)). Agonism at S1P(1) was displayed in vivo by induction of lymphopenia. A stereochemical preference of the quaternary carbon was crucial for phosphorylation by the kinases and alters binding affinities at the S1P receptors. Oxazole and oxadiazole compounds are superior kinase substrates to FTY720, the prototypical prodrug immunomodulator, fingolimod (FTY720). The oxazole-derived structure was the most active for human SPHK2. Imidazole analogues were less active substrates for SPHKs, but more potent and selective agonists of the S1P(1) receptor; additionally, the imidazole class of compounds rendered mice lymphopenic.

B lymphocytes exit lymph nodes through cortical lymphatic sinusoids by a mechanism independent of sphingosine-1-phosphate-mediated chemotaxis

Sphingosine-1-phosphate (S1P) helps mediate lymphocyte egress from lymph nodes, yet many mechanistic questions remain. Here, we show the presence of B lymphocyte egress sites located in the lymph node cortex close to lymph node follicles. B cells exited lymph nodes by squeezing through apparent portals in the lymphatic endothelium of these sinusoids. Treatment with the S1P receptor agonist FTY720 emptied the cortical sinusoids of lymphocytes, blocked lymphatic endothelial penetration, and displaced B lymphocytes into the T cell zone. S1pr3(-/-) B cells, which lack chemoattractant responses to S1P, transited lymph nodes normally, whereas Gnai2(-/-) B cells, which have impaired responses to chemokines and S1P, transited more rapidly than did wild-type cells. This study identifies a major site of B lymphocyte lymph node egress, shows that FTY720 treatment blocks passage through the cortical lymphatic endothelium, and argues against a functional role for S1P chemotaxis in B lymphocyte egress.

Sustained moderate visual loss as a predictive end point for visual loss in non-proliferative diabetic retinopathy

PURPOSE

In PKC-DRS2, the efficacy of the oral PKC-beta inhibitor, ruboxistaurin 32 mg/day, was measured by the primary end point of sustained moderate visual loss (SMVL: a > or = 15 letter decrease from baseline on the ETDRS (Early Treatment Diabetic Retinopathy Study) chart sustained at least for the last 6 months of study participation). We now evaluate whether SMVL is more accurate than moderate visual loss (MVL: a single occurrence of a decrease from baseline of > or = 15 ETDRS letters) for predicting future visual loss.

METHODS

Study eyes with moderately severe to very-severe non-proliferative diabetic retinopathy, best-corrected visual acuity of at least 45 letters on the ETDRS chart (approximately Snellen 20/125), and no prior pan retinal photocoagulation were evaluated in 506 patients (869 eyes) who completed 36 months of treatment.

RESULTS

Sixty-five percentage (26/40) of study eyes with the onset of SMVL within 24 months of enrolment still had SMVL at study completion (36 months). In comparison, only 24% (30/126) with MVL within 24 months had SMVL at study completion. Analyses based on data from 6, 12, and 18 months of treatment were similar.

CONCLUSIONS

SMVL is a more predictable measure of subsequent visual loss than is a single time point measure of MVL.

Collaboration in caring for psychiatric inpatients: Family physicians team up with psychiatrists and psychiatric nurses

PROBLEM BEING ADDRESSED

The standard organization of psychiatric inpatient care at our hospital involved consultations with various specialist physicians visiting the psychiatry wards to assess patients' medical needs and to provide appropriate interventions. We thought that this type of clinical care pathway might not be leading to the best integration and timeliness of patient care, the most efficient use of specialist resources, or the least cost to the health care system.

OBJECTIVE OF PROGRAM

To initiate a protocol that would involve an FP visiting all the psychiatry wards daily (on weekdays) to conduct medical consultations. We hoped this program would improve the timeliness and integration of patient care, reduce patients' length of stay in hospital, and alter the pattern of specialist consultations.

PROGRAM DESCRIPTION

The FP consulted on patients referred by psychiatrists and registered psychiatric nurses; carried out assessments; initiated treatment of commonmedical problems; referred to other specialists when necessary; and made arrangements for follow-up care as appropriate.

CONCLUSION

The FP consultations improved patient care in several ways, was highly valued by staff, and modified the pattern of specialist consultations on participatingpsychiatry wards.

Early retinopathy progression in four randomized trials comparing insulin glargine and NPH [corrected] insulin

Early worsening of diabetic retinopathy, characterized by cotton wool spots, intraretinal microvascular abnormalities and/or macular edema, can occur following improvement of glycemic control. In four randomized 28- to 52-week clinical trials comparing insulin glargine and NPH insulin in regard to glycemic control and frequency of hypoglycemia, ophthalmologic examinations and fundus photographs were included to assess frequency of early worsening of retinopathy or other early adverse ocular effects. Retinopathy progression rates at 28 weeks were 7-12% by clinical examination and 3-8% by photographic grading; corresponding rates of clinically significant macular edema (CSME) were 1-8% and 1-4%, respectively. Optic disc swelling was not observed clinically or in photographs. Two of the 24 possible comparisons (four trials, three outcomes, two assessment methods), both of which were photographic assessments in type 2 diabetes, were in/near the nominally significant range and favored NPH insulin: 28-week rates of >or=3-step retinopathy progression (insulin glargine: 16/213, 7.5%; NPH insulin: 6/220, 2.7%; p=0.028) and 52-week CSME rates (26/233, 11.2% and 14/214, 6.5%, respectively; p=0.098). Because the between-treatment differences were small and inconsistent across trials and assessment methods, and because overall rates were consistent with the natural course of diabetic retinopathy, we conclude that it is unlikely that insulin glargine carries a higher risk of early worsening or other early adverse effect than NPH insulin. These trials tended to exclude a large early adverse effect, such as optic disc swelling, but cannot assess longer-term effects; a 5-year randomized trial of insulin glargine versus NPH insulin has been initiated. Data from this manuscript have been presented as posters and published in abstract form at the European Association for the Study of Diabetes 2001 ( DIABETOLOGIA 44(Suppl 1):I-IV(A287), 2001) and the Latin American Diabetes Association 2001 (11-15 November 2001, Punta del Este, Uruguay; Poster 180) congresses.

Harderian gland adenectomy: a method to eliminate confounding radio-opacity in the assessment of rat brain metabolism by 18F-fluoro-2-deoxy-D-glucose positron emission tomography

The 18F isotope of fluoro-2-deoxy-D-glucose (FDG) is a radiotracer commonly used in positron emission tomography (PET) for determining regional metabolic activity in the brain. However, in rats and many other species with nictitating membranes, harderian glands located just behind the eyes aggressively incorporate 18F-FDG to the extent that PET images of the brain become obscured. This radioactive spillover, or 'partial volume error,' combined with the limited spatial resolution of microPET scanners (1.5 to 2 mm) may markedly reduce the ability to quantify neuronal activity in frontal brain structures. Theoretically, surgical removal of the harderian glands before 18F-FDG injection would eliminate the confounding uptake of the radioactive tracer and thereby permit visualization of glucose metabolism in the frontal brain. We conducted a pilot study of unilateral harderian gland adenectomy, leaving the contralateral gland intact for comparison. At 1 wk after surgery, each rat was injected intravenously with 18F-FDG, and 40 min later underwent brain microPET for 20 min. Review of the resulting images showed that the frontal cortex on the surgical side was defined more clearly, with only background 18F-FDG accumulation in the surgical bed. Activity in the frontal cortex on the intact side was obscured by intense accumulation of 18F-FDG in the harderian gland. By reducing partial volume error, this simple surgical procedure may become a valuable tool for visualization of the frontal cortex of rat brain by 18F-FDG microPET imaging.

Akt/cAMP-responsive element binding protein/cyclin D1 network: a novel target for prostate cancer inhibition in transgenic adenocarcinoma of mouse prostate model mediated by Nexrutine, a Phellodendron amurense bark extract

PURPOSE

Development of prostate cancer prevention strategies is an important priority to overcome high incidence, morbidity, and mortality. Recently, we showed that Nexrutine, an herbal extract, inhibits prostate cancer cell proliferation through modulation of Akt and cAMP-responsive element binding protein (CREB)-mediated signaling pathways. However, it is unknown if Nexrutine can be developed as a dietary supplement for the prevention of prostate cancer. In this study, we used the transgenic adenocarcinoma of mouse prostate (TRAMP) model to examine the ability of Nexrutine to protect TRAMP mice from developing prostate cancer.

EXPERIMENTAL DESIGN

Eight-week-old TRAMP mice were fed with pelleted diet containing 300 and 600 mg/kg Nexrutine for 20 weeks. Efficacy of Nexrutine was evaluated by magnetic resonance imaging at 18 and 28 weeks of progression and histologic analysis of prostate tumor or tissue at the termination of the experiment. Tumor tissue was analyzed for modulation of various signaling molecules.

RESULTS

We show that Nexrutine significantly suppressed palpable tumors and progression of cancer in the TRAMP model. Expression of total and phosphorylated Akt, CREB, and cyclin D1 was significantly reduced in prostate tissue from Nexrutine intervention group compared with tumors from control animals. Nexrutine also inhibited cyclin D1 transcriptional activity in androgen-independent PC-3 cells. Overexpression of kinase dead Akt mutant or phosphorylation-defective CREB inhibited cyclin D1 transcriptional activity.

CONCLUSIONS

The current study shows that Nexrutine-mediated targeting of Akt/CREB-induced activation of cyclin D1 prevents the progression of prostate cancer. Expression of CREB and phosphorylated CREB increased in human prostate tumors compared with normal tissue, suggesting their potential use as prognostic markers.